List of possible malfunctions | Diagnostics | Methods of elimination |
The crankshaft does not turn with the starter | ||
| The battery is discharged | The voltage at the battery terminals with the consumers switched off is below 12 V. When the starter is turned on, a crackling sound may be heard from under the hood | Charge the battery; if it doesn't charge, replace it |
| Decrease in battery capacity | The voltage at the battery terminals with the consumers switched off is more than 12 V, but when the starter is switched on it drops below 6–8 V. In this case, a crackling sound may be heard from under the hood. Make sure that there is no short circuit in the starter (see below) | Charge the battery with a small current (no more than 1 A); if its functionality is not restored, replace it |
| The battery terminals are oxidized or not tightly connected | When the starter is turned on, the voltage in the on-board network drops much more than at the terminals of the battery. When the starter is turned on, a crackling sound may be heard from under the hood | Crimp the terminals, clean the contacts, lubricate them with any plastic grease |
| The oil in the engine is too thick | Check the oil on the dipstick: the drop should be liquid | Replace the oil with one that is appropriate for the climate conditions (see Fuels, lubricants and operating fluids used) |
| The engine or attachments are jammed | Check the free rotation of the crankshaft, generator, coolant pump. To do this, you can turn the crankshaft by the pulley nut with a special key, the crank handle by the ratchet (on those cars where there is a hole for it) or push the car with the help of 1-2 people, turning on the highest gear | Repair engine, generator, replace coolant pump |
| The starter traction relay control circuit is faulty: the wires are damaged, their tips are oxidized or loose, contacts "30" and "50" of the ignition switch or starter relay do not close | When turning the key to the "starter" position, the traction relay does not operate (no click under the hood). Check if 12 V is supplied to the control contact of the traction relay | Strip and crimp the wire ends; replace the faulty ignition switch or its contact part, starter relay |
| Short circuit or open circuit in the starter relay pull-in winding. Relay anchor sticking (anchor misalignment, surface contamination, corrosion, etc.) | When turning the key to the "starter" position, the traction relay does not operate (no click under the hood), but 12 V is supplied to the control contact of the traction relay. Remove the starter, relay, check its operation | Replace the faulty traction relay |
| Oxidized contacts of the traction relay or wires, poor contact "mass" | When the starter is turned on, a click is heard under the hood, but the starter anchor does not rotate. Check the resistance of the "battery - starter" circuit with an ohmmeter, including the "ground" wires (from the body to the clutch housing and from the body to the cylinder head). If the circuits are OK, remove the starter and check its operation | Tighten the wire tips, crimp the terminals. Faulty traction relay (or starter) replace |
| Collector burnout, brushes sticking or wearing out | Make sure the traction relay is working properly. You can supply power to the starter bypassing the relay. (Be careful to avoid sparking near the battery!) On the removed starter, check the force of pressing the brushes to the collector, their residual height, and the wear of the collector | Clean the collector with fine-grained glass sandpaper, wash with unleaded gasoline, ensure free movement of the brushes in the sockets. If the collector is heavily worn, replace the starter |
| Open or short circuit in the armature winding | Make sure the traction relay is working properly. You can supply power to the starter bypassing the relay. (Be careful to avoid sparking near the battery!) The armature winding is checked after disassembling the starter with an ohmmeter or by darkening of the insulation | Replace starter |
| Open or short circuit in the holding winding of the starter relay | When the starter is turned on, a crackling sound is heard from under the hood. The voltage on the battery and on the control contact of the traction relay is within normal limits. The relay is checked with an ohmmeter or by its excessive heating | Replace the starter solenoid relay |
| Freewheel clutch slippage | When the starter is turned on, the anchor rotates, but the flywheel is stationary. First, make sure that the traction relay is in good condition and the drive gear engages with the flywheel ring gear (on the removed starter the gear does not stick on the axle, the teeth of the flywheel ring gear are in good condition). | Replace the clutch or starter. |
| The starter clutch gear or flywheel ring gear teeth are damaged | Inspection after disassembling units | Replace the crown or flywheel. You can re-press the old flywheel crown by turning it over with the unworn side. |
| The ring gear rotates on the flywheel | Squealing, howling from the clutch housing (when the starter is turned on, the ring gear rotates, the flywheel is stationary; the crankshaft may turn jerkily, with slippage) | Replace ring gear or flywheel |
Loud noise when starting the starter | ||
| The starter is mounted on the engine at an angle, its mount is loose, or the cover on the drive side is broken | Inspection | Tighten threaded connections to the specified torque, replace broken, worn parts or the starter assembly |
| The starter pole mount has become loose (the anchor catches on it) | Disassemble the starter, inspect it, check the alignment of the poles and the gap between them and the anchor | Tighten the pole mount or replace the starter |
| Excessive wear of bearing bushings or anchor shaft journals | Inspection after disassembling the starter | Replace starter |
| The ring gear rotates on the flywheel | When the starter is turned on, the toothed ring rotates, the flywheel is stationary. Squealing, howling from the clutch housing | Replace flywheel crown |
| The teeth of the starter drive gear or (more often) the flywheel ring gear are worn out | Inspection | Replace the starter or flywheel. You can re-press the old flywheel ring by turning it over with the unworn side. |
| The gear does not disengage from the flywheel: the drive lever is jammed; the overrunning clutch or starter traction relay is loose or broken; the clutch on the armature shaft splines or the traction relay core is jammed; the ignition switch is faulty (contacts "30" and "50" do not open) or the starter relay is faulty | Checking the removed starter, inspection after disassembly. The operation of the ignition switch can be checked with an ohmmeter or visually by removing its contact part | Replace the starter solenoid or starter assembly; ignition switch contact group or switch assembly, starter relay |
The crankshaft is turned by the starter, but the engine does not start | ||
| There is no fuel in the tank | According to the fuel level indicator and control lamp | Fill with fuel |
| The battery is discharged | The voltage at the battery terminals with the consumers switched off is below 12 V. After several revolutions, the starter stops turning the crankshaft, and a crackling sound may be heard from under the hood | Charge the battery; if it doesn't charge, replace it |
| Reduced battery capacity | The voltage at the battery terminals with the consumers switched off is more than 12 V, but when the starter is switched on it drops to 6–8 V. After several revolutions, the starter stops turning the crankshaft, and a crackling sound may be heard from under the hood. Make sure that there is no short circuit in the starter (see above) | Charge the battery with a small current (no more than 1 A); if its functionality is not restored, replace it |
| The battery terminals are oxidized or not tightly connected | When the starter is turned on, the voltage in the on-board network drops much more than at the terminals of the battery. At the same time, a crackling sound may be heard from under the hood | Crimp the terminals, clean the contacts, lubricate them with any plastic grease |
| Low voltage circuit fault | Check with the ignition on whether voltage is supplied to the ignition coil. Use an ohmmeter to check the circuit from the ignition coil to the contacts of the breaker [K] or to the switch [B] | Clean oxidized tips, tighten loose wire fastenings, replace damaged wires, ignition switch or its contact part |
| [K] The gap between the breaker contacts is not adjusted | A gap of 0.35–0.45 mm is checked with a flat feeler gauge | Adjust the gap |
| [K] The contact group of the breaker-distributor is faulty: the contacts are damaged or oily, the spring is weak, the moving contact is stuck on the axis | Inspection, testing with an autotester (see Ignition system) | Clean worn contacts with a file (check that they are parallel and that there is no offset) and wipe dry. If the spring is weakened, the contacts are jammed or heavily worn, replace the contact group |
| [K] Capacitor is faulty | Remove the central wire from the ignition distributor and secure its tip at a distance of 5-6 mm from the vehicle ground. Turn on the ignition and manually open the breaker contacts (slightly turning it by the runner). If a strong, clicking blue spark jumps between the wire and the "ground", the capacitor is in good condition. If the spark is weak, thread-like or absent altogether, short-circuit the contacts with a piece of wire or a screwdriver. In this case, an increase in the spark will indicate a capacitor malfunction | Replace the faulty capacitor |
| [B] The Hall sensor or its electrical circuits are faulty | Determined by a voltmeter (see Ignition system) or replacing the sensor with a known good one | Replace the faulty sensor |
| [B] The switch is faulty | Replace the switch with a known good one | Replace the faulty switch |
| Damage to high-voltage devices and circuits | Having securely fastened the end of the high-voltage wire at a distance of 5–6 mm from the vehicle's ground, crank the engine with the starter (do not touch high voltage circuits!). A spark should regularly jump between the wire and the ground (for testing, use only known good high voltage wires). If there is no spark at the ignition coil terminal, the coil is faulty; if there is no spark at the ignition distributor terminal or terminals, the distributor rotor or cover is faulty. Burnout of the rotor or cover is determined visually. The rotor resistor is checked for serviceability with an ohmmeter | Replace the faulty coil, high-voltage wires, and runner. In severe operating conditions (salt on the roads, frosts alternating with thaws) it is advisable to replace the wires every 5 years |
| High voltage wires are connected to the ignition distributor in the wrong order | Inspection | Connect the wires according to the firing order of the cylinders (1-3-4-2) |
| The gap between the spark plug electrodes is not within the norm | The gap of 0.5–0.6 mm [K] (0.7–0.8 mm [B]) is checked with a round feeler gauge | By bending the side electrode, set the required gap or replace the spark plugs |
| Defective spark plugs | Replace the spark plugs with known good ones or check them on a special stand [service station]. The absence of external damage and sparking between the electrodes on the removed spark plug do not allow us to conclude that it is in working order | Replace faulty spark plugs |
| Incorrect ignition timing | Cm. Ignition system | Adjust the ignition timing |
| The valve timing is out of order | Check that the marks on the crankshaft and camshaft match (see Engine) | Set the correct relative position of the shafts (using marks) |
| There is no 12 V supplied to the idle speed solenoid valve or the valve itself is faulty | We check the supply voltage and the absence of a break in the valve winding with an autotester. The valve operation can be determined by a click | You can temporarily apply voltage to the valve directly from the "+" terminal of the battery (preferably through a fuse) or, having unscrewed the faulty valve, remove its plastic shut-off needle or replace the valve with a nozzle holder (in this case, after turning off the ignition, the engine may give flashes) |
| Fuel filters are clogged, water in the fuel system is frozen, hoses are pinched, fuel line tubes are deformed | When the engine is cranked by the starter, there is no smell of gasoline from the exhaust pipe. There is no gasoline in the carburetor float chamber - when you press the "gas", there is no stream of fuel from the accelerator pump sprayer (visible when the air filter housing cover is removed). | In winter, roll your car into a warm garage and blow it out (tire pump) the fuel system from the engine to the gas tank, replace any defective hoses and tubes |
| The fuel pump is not working | Remove the fuel supply hose from the carburetor and, holding it with your finger, pump fuel with the pump lever. A working pump should develop noticeable pressure, which should be maintained in the hose for at least 10 seconds. Check the correct installation of the fuel pump (pusher protrusion) (cm. Engine power supply system) | Replace the fuel pump or its diaphragms, adjust the tappet protrusion (mounting gaskets), replace the pusher if necessary |
| The carburetor starter or its drive is faulty or not adjusted | Cm. Carburetor | Adjust the starting device, replace worn parts |
| Suction of foreign air into the intake manifold | Inspect the joints, check the fit of the hoses, fittings, and the tightening of the clamps. Temporarily disconnect the brake booster by pinching the corresponding hose (the force on the brake pedal will increase significantly!) | Torn gaskets, parts with deformed flanges, faulty vacuum booster - replace |
| The carburetor fuel jets are clogged (main fuel and idle) | The engine starts only after several vigorous pressings on the gas pedal. A hot engine starts better than a cold one. | Wash with solvent or acetone and blow out the jets, if heavily soiled, clean them with a fishing line or a needle made of soft wood. Tightly screw the jets in (do not damage the threads and the nozzle!) |
| The fuel jets of the carburetor are not tightly screwed in. The air jets are clogged | There is a strong smell of gasoline coming from the exhaust pipe, the cold engine starts better than the hot one. The fuel level in the float chamber is normal (to check, remove the carburetor cover) (cm. Carburetor) | Wash with solvent or acetone and blow out the jets, if heavily soiled, clean them with a fishing line or a needle made of soft wood. Tightly screw the jets in (do not damage the threads and the nozzle!) |
| Excessive fuel level in the carburetor float chamber | A strong smell of gasoline is felt from the exhaust pipe, a cold engine starts better than a warm one. Remove the carburetor cover, check the tightness of the float, ease of its movement and the absence of contact with the walls of the float chamber, the tightness of the needle valve. Turning the cover upside down with the float upward, pump gasoline with the manual fuel pump lever. The slightest leak of gasoline from under the needle or valve seat is unacceptable | Replace the needle valve, adjust the fuel level in the float chamber (see Carburetor) |
| Over-enriched mixture due to gasoline leaking into the engine crankcase through a torn diaphragm in the fuel pump | The oil on the dipstick smells like gasoline, the low oil pressure indicator may light up at idle speed | Replace the fuel pump or its diaphragms; if there is a lot of gasoline in the oil, then there is oil |
In cold weather, the engine starts easily, but immediately stalls and only after several attempts to start does it begin to work steadily | ||
| Faulty (the telescopic rod spring is weak, the diaphragm is torn) or the carburetor starting device is not adjusted | Checking the functionality of the starting device: short-circuit the wire from the ignition coil to ground, remove the air filter housing cover, completely close the air damper and crank the engine with the starter (ask for an assistant) – the valve should not open slightly. Insert the high-voltage wire into the distributor and ask to start the engine (it should be cold) – as soon as the engine starts running, the damper should open by 5 mm (see Carburetor) | Replace the diaphragm, telescopic rod or select a stiffer spring (see Carburetor) |
The engine takes a long time to start | ||
| Gasoline evaporated from the carburetor float chamber (after a long period of parking, especially in hot weather) | — | After a long period of parking, you can pump up the gasoline using the manual fuel pump lever |
Engine runs rough or stalls at idle | ||
| The engine is not warmed up | According to the temperature indicator | Warm up the engine to operating temperature |
| Clogged fuel lines, fuel filters, water in fuel | Inspection, replacement | Clean the fuel intake screen, fuel filters, if you suspect low quality gasoline, especially before the winter season, use special fuel additives that bind water. After using them, it is recommended to wash or replace the fuel filters |
| Engine idle speed adjustment is out of adjustment | Cm. Carburetor | Adjust idle speed (see Carburetor) |
| Suction of foreign air into the intake manifold | Inspect the joints, check the fit of the hoses, fittings, and the tightening of the clamps. Temporarily disconnect the brake booster by pinching the corresponding hose (the force on the brake pedal will increase significantly!) | Torn gaskets, parts with deformed flanges, faulty vacuum booster - replace |
| The carburetor fuel jets are clogged (main fuel and idle) | The engine starts only after several vigorous pressings on the gas pedal. A hot engine starts better than a cold one. | Wash with gasoline or acetone and blow out the jets; if heavily soiled, clean them with a fishing line or a needle made of soft wood. Tightly screw the jets (do not damage the thread and the jet!) |
| Insufficient fuel level in the carburetor float chamber | The engine starts poorly and "pulls" poorly. There may be pops in the carburetor. When the "choke" button is pulled out, the jerks and dips decrease or disappear completely. To check the fuel level, remove the carburetor cover (see Carburetor) | Adjust the fuel level (see Carburetor) |
| The fuel pump does not create the required pressure in the system | Remove the fuel supply hose from the carburetor and, holding it with your finger, pump fuel with the pump lever. A working pump should develop noticeable pressure, which should be maintained in the hose for at least 10 seconds. Check the correct installation of the fuel pump (pusher protrusion) (cm. Engine power supply system) | Replace the fuel pump or its diaphragms, adjust the tappet protrusion (mounting gaskets), replace the pusher if necessary |
| The fuel jets of the carburetor are not tightly screwed in. The air jets are clogged | There is a strong smell of gasoline coming from the exhaust pipe, the cold engine starts better than the hot one. The fuel level in the float chamber is normal (to check, remove the carburetor cover) (cm. Carburetor) | Wash with gasoline or acetone and blow out the jets; if heavily soiled, clean them with a fishing line or a needle made of soft wood. Tightly screw the jets in (do not damage the threads and the nozzle!) |
| Excessive fuel level in the carburetor float chamber | There is a strong smell of gasoline coming from the exhaust pipe, a cold engine starts better than a hot one. Remove the top cover of the carburetor, check the tightness of the float, ease of movement and absence of contact with the walls of the float chamber. Checking the tightness of the needle valve: remove the carburetor cover and turn it upside down with the float, pump gasoline with the fuel pump lever. The slightest leak of gasoline from under the needle or valve seat is unacceptable | Replace the needle valve, adjust the fuel level in the float chamber (see Carburetor) |
| Over-enrichment of the mixture due to gasoline leaking into the engine crankcase through a torn diaphragm of the fuel pump | The oil on the dipstick smells like gasoline, the low oil pressure indicator may light up at idle speed | Replace the fuel pump or its diaphragms; if there is a lot of gasoline in the oil, then there is oil |
| There is no 12 V supplied to the idle speed solenoid valve or the valve itself is faulty | We check the supply voltage and the absence of a break in the valve winding with an autotester. The valve operation can be determined by a click | You can temporarily apply voltage to the valve directly from the "+" terminal of the battery (preferably through a fuse) or, having unscrewed the faulty valve, remove its plastic shut-off needle or replace the valve with a nozzle holder (in this case, after turning off the ignition, the engine may give flashes) |
| The gap between the spark plug electrodes is not within the norm | The gap between the spark plug electrodes is not within the norm | By bending the side electrode, set the required gap or replace the spark plugs |
| Heavy carbon deposits on spark plug electrodes; carbon particles getting into the gap between the electrodes | Inspection | Clean the spark plugs with compressed air or mechanically (do not damage the insulator!), make sure they are in working order [STO](the absence of external damage and sparking between the electrodes on the removed spark plug does not allow us to conclude that it is in working order). Identify and eliminate the cause of increased carbon formation in the combustion chamber, replace the spark plugs if necessary |
| Defective spark plugs: current leakage through cracks in the insulator or carbon deposits on the thermal cone, poor contact in the central electrode assembly | Replace the spark plugs with known good ones or check them on a special stand [service station]. The absence of external damage and sparking between the electrodes on the removed spark plug do not allow us to conclude that it is in working order | Replace faulty spark plugs |
| Damage to high-voltage devices and circuits | Having securely fastened the end of the high-voltage wire at a distance of 5–6 mm from the vehicle's ground, crank the engine with the starter (do not touch high voltage circuits!). A spark should regularly jump between the wire and the ground (for testing, use only known good I/O cables). If there is no spark at the ignition coil terminal, the coil is faulty; if at the ignition distributor terminal/terminals, the distributor rotor or cover is faulty. Burnouts of the rotor or cover are determined visually. The serviceability of the rotor resistor is checked with an ohmmeter | Replace the faulty coil, high-voltage wires, and runner. In severe operating conditions (salt on the roads, frosts alternating with thaws) it is advisable to replace the wires every 5 years |
| Wear, damage, weakening of the carbon spring in the distributor cap | Inspection with the cover removed | Replace the distributor cap or the carbon with the spring |
| Incorrect ignition timing | Cm. Ignition system | Adjust the ignition timing |
| Poor contact in the low voltage circuit | Check with the ignition on whether voltage is supplied to the ignition coil. Use an ohmmeter to check the circuit from the ignition coil to the contacts of the breaker [K] or to the switch [B] | Clean oxidized tips, tighten loose wire fastenings, replace damaged wires, ignition switch or its contact part |
| [K] The contact group of the breaker-distributor is faulty: the contacts are damaged or oily, the spring is weak, the moving contact is stuck on the axis | Inspection, testing with an autotester (see Ignition system) | Clean worn contacts with a file (check that they are parallel and that there is no offset) and wipe dry. If the spring is weakened, the contacts are jammed or heavily worn, replace the contact group |
| [B] The Hall sensor or its electrical circuits are faulty | Determined by a voltmeter (see Ignition system) or replacing the sensor with a known good one | Replace the faulty sensor |
| [B] The switch is faulty | Replace the switch with a known good one | Replace the faulty switch |
| [K] Reduced capacity of the capacitor or poor contact in its circuit | Check the circuit with an autotester. To check the capacitor, remove the central wire from the ignition distributor and secure its tip at a distance of 5-6 mm from the vehicle's "ground". Turn on the ignition and manually open the breaker contacts (slightly turning it by the runner). If a strong, clicking blue spark jumps between the wire and the "ground", the capacitor is in good condition. If the spark is weak, thread-like or absent altogether, short-circuit the contacts with a piece of wire or a screwdriver. In this case, an increase in the spark will indicate a capacitor malfunction | If you suspect a capacitor is faulty, replace it |
| Weakening or breakage of the springs of the centrifugal regulator weights of the ignition distributor, loss of damper rings of the weights, jamming of the weights | Visually and on a special stand [STO] | Replace the ignition distributor |
| Vacuum advance regulator operation is fuzzy: when vacuum is removed, the plate does not return to its original position, large play in the bearing | Inspection. The vacuum regulator characteristics are taken on a special stand [STO] | Fix the jam, replace the faulty vacuum regulator or distributor assembly |
| The valve timing is out of order | Check that the marks on the crankshaft and camshaft match (see Engine) | Set the correct relative position of the shafts (using marks) |
| Valve clearances not adjusted | Checked with a set of feeler gauges (see Engine) | Adjust the gaps |
| Severe wear of camshaft lobes | Inspection after partial disassembly of the engine | Replace the camshaft |
| Low compression in cylinders (less than 10 kgf/cm²) or its great unevenness across the cylinders (more than 2 kgf/cm²): wear or damage to valves, seats, wear, sticking or breakage of piston rings | Warm up the engine to operating temperature and remove the spark plugs. Press the gas pedal all the way down and, inserting a compression gauge into the spark plug holes, turn the crankshaft with the starter (work together). In this case, the high-voltage wire of the ignition coil should be shorted to ground. Repeat the measurements by pouring 10–15 cm³ of engine oil into the cylinders through the spark plug holes. In those cylinders where the compression has increased by more than 2 kgf/cm², the rings may be heavily worn, broken or stuck. If the compression remains below 10 kgf/cm², the valves or their seats may be worn or damaged | Replace rings, pistons. Repair the cylinder block [STO]. Grind the valves to the seats, if necessary, replace the valves, their guide bushings, grind the seats [STO] |
Low idle speed | ||
| Idle adjustment is out of order engine stroke | Cm. Carburetor | Adjust idle speed |
| Incorrect ignition timing | Cm. Ignition system | Adjust the ignition timing |
| The engine is not warmed up | According to the temperature indicator | Warm up the engine to operating temperature |
| Suction of foreign matter air into the intake manifold | Inspect the joints, check the fit of the hoses, fittings, and the tightening of the clamps. Temporarily disconnect the brake booster by pinching the corresponding hose (the force on the brake pedal will increase significantly!) | Torn gaskets, parts with deformed flanges, faulty vacuum booster - replace |
| The carburetor fuel jets are clogged (main fuel and idle) | The engine starts only after several vigorous pressings on the gas pedal. A hot engine starts better than a cold one. | Wash with gasoline or acetone and blow out the jets; if heavily soiled, clean them with a fishing line or a needle made of soft wood. Tightly screw the jets in (do not damage the threads and the nozzle!) |
| Insufficient fuel level in the carburetor float chamber | The engine starts poorly and "pulls" poorly. There may be pops in the carburetor. When the "choke" button is pulled out, the jerks and dips decrease or disappear completely. To check the fuel level, remove the carburetor cover (see Carburetor) | Adjust the fuel level (see Carburetor) |
| Excessive fuel level in the carburetor float chamber | There is a strong smell of gasoline coming from the exhaust pipe, a cold engine starts better than a hot one. Remove the top cover of the carburetor, check the tightness of the float, ease of movement and absence of contact with the walls of the float chamber. Checking the tightness of the needle valve: remove the carburetor cover and turn it upside down with the float, pump gasoline with the fuel pump lever. The slightest leak of gasoline from under the needle or valve seat is unacceptable | Replace the leaky needle valve, adjust the fuel level in the float chamber (see Carburetor) |
| The fuel jets of the carburetor are not tightly screwed in. The air jets are clogged | There is a strong smell of gasoline coming from the exhaust pipe, the cold engine starts better than the hot one. The fuel level in the float chamber is normal (to check, remove the carburetor cover) (cm. Carburetor) | Wash with gasoline or acetone and blow out the jets; if heavily soiled, clean them with a fishing line or a needle made of soft wood. Tightly screw the jets in (do not damage the threads and the nozzle!) |
| Increased air flow resistance in the intake tract | Check the air filter element, intake tract (absence of foreign objects, leaves, etc.) | Clean the intake tract, replace the dirty air filter element |
High idle speed | ||
| Engine idle speed adjustment is out of adjustment | Cm. Carburetor | Adjust idle speed |
| Long-term driving at high engine speeds | After 30–40 seconds of idling, the revs drop to normal | It is not a malfunction |
| Throttle actuator (gas pedal) malfunction, return spring on carburetor weakened | Check the pedal travel, clearance in the drive (free pedal travel), make sure that there are no jammed parts | Replace defective parts, lubricate the cable with engine oil |
| The carburetor starter or its drive is faulty or not adjusted | Cm. Carburetor | Adjust the starting device, replace worn parts |
| Incorrect ignition timing | Cm. Ignition system | Adjust the ignition timing |
| Excessive fuel level in the carburetor float chamber | There is a strong smell of gasoline coming from the exhaust pipe, a cold engine starts better than a hot one. Remove the top cover of the carburetor, check the tightness of the float, ease of movement and absence of contact with the walls of the float chamber. Checking the tightness of the needle valve: remove the carburetor cover and turn it upside down with the float, pump gasoline with the fuel pump lever. The slightest leak of gasoline from under the needle or valve seat is unacceptable | Replace the leaky needle valve, adjust the fuel level in the float chamber |
| The idle air jet is clogged | Inspection after disassembly | Wash with unleaded gasoline or acetone and blow out the jet. If heavily soiled, clean it with a fishing line or a needle made of soft wood. Flush the crankcase ventilation system |
| Over-enriched mixture due to gasoline leaking into the engine crankcase through a torn diaphragm in the fuel pump | The oil on the dipstick smells like gasoline, the low oil pressure indicator may light up at idle speed | Replace the fuel pump or its diaphragms; if there is a lot of gasoline in the oil, then there is oil |
| The carburetor throttle valves do not close completely | When held up to the light, a gap is visible between the throttle valve and the walls of the mixing chamber | Use the stop screws of the flaps to achieve their complete closure. The flaps should open easily, without jamming. After adjustment, fill the screws with paint |
| The carburetor flaps are mounted on skewed axles and do not close in any position of the stop screws | Inspection | Having supported the damper axes on a suitable stop (so as not to bend them), loosen the screws and, having correctly oriented the flaps, tighten them [STO](or replace the carburetor or throttle body) |
| Foreign objects getting under the throttle valve or its drive | Inspection | Remove foreign object, check damper operation |
In cold weather, the engine stalls soon after starting to move, but after a short period of standing, it starts again | ||
| An ice plug has formed in the carburetor diffuser (the heated air supply hose is not connected to the outlet manifold) | Inspection | Secure the hose to the heated air intake pipe with a clamp. |
In hot weather, the engine stops spontaneously | ||
| Steam lock in the fuel system | Inspect the fuel lines, blow out the line with a tire pump | Eliminate kinks in hoses, replace deformed tubes |
The engine does not develop full power and does not have sufficient throttle response. Jerks and dips when driving the car | ||
| The engine is not warmed up | According to the temperature indicator | Warm up the engine to operating temperature |
| There is little fuel in the tank | According to the fuel level indicator and control lamp | Add fuel |
| The fuel pump does not create the required pressure in the system | Remove the fuel supply hose from the carburetor and, holding it with your finger, pump fuel with the pump lever. A working pump should develop noticeable pressure, which should be maintained in the hose for at least 10 seconds. Check the correct installation of the fuel pump (pusher protrusion) (cm. Engine power supply system) | Replace the fuel pump or its diaphragms, adjust the tappet protrusion (mounting gaskets), replace the pusher if necessary |
| Clogged fuel lines, fuel filters, pinched hoses, deformed tubes, water in fuel | Inspection | Clean the fuel intake screen, wash or replace filters, defective tubes, eliminate kinks in hoses. In winter, roll the car into a warm garage, blow out (tire pump) the power supply system from the engine to the gas tank. If you suspect low quality gasoline, especially before the winter season, use special fuel additives that bind water. After using them, it is recommended to flush or replace the fuel filters |
| Insufficient fuel level in the carburetor float chamber | Insufficient fuel level in the carburetor float chamber | Adjust the fuel level (see Engine power supply system) |
| The carburetor jets and channels are clogged. The jets are not tightly screwed in | Inspect and blow out the channels and jets | Wash with gasoline or acetone and blow out the jets; if heavily soiled, clean them with a fishing line or a needle made of soft wood. Tightly screw the jets in (do not damage the threads and the nozzle!) |
| The diaphragm of the accelerator pump is torn, its lever is jammed, the spray nozzle or supply channels are clogged | Check the pump feed, the direction of the jet, and the absence of gasoline leakage from under the diaphragm. Make sure the accelerator pump lever moves freely | Replace damaged parts, tighten threaded connections, blow out valves |
| Suction of foreign air into the intake manifold | Inspect the joints, check the fit of the hoses, fittings, and the tightening of the clamps. Disconnect the brake booster briefly by pinching the corresponding hose (caution: the force on the brake pedal will increase significantly!) | Torn gaskets, parts with deformed flanges, faulty vacuum booster - replace |
| Excessive fuel level in the carburetor float chamber | There is a strong smell of gasoline coming from the exhaust pipe, a cold engine starts better than a hot one. Remove the top cover of the carburetor, check the tightness of the float, ease of movement and absence of contact with the walls of the float chamber. Checking the tightness of the needle valve: remove the carburetor cover and turn it upside down with the float upwards, pump gasoline with the fuel pump lever. The slightest leak of gasoline from under the needle or valve seat is unacceptable (see Carburetor) | Replace the needle valve, adjust the fuel level in the float chamber |
| Over-enriched mixture due to gasoline leaking into the engine crankcase through a torn diaphragm in the fuel pump | The oil on the dipstick smells like gasoline, the low oil pressure indicator may light up at idle speed, the idle speed is unstable | Replace the fuel pump or its diaphragms; if there is a lot of gasoline in the oil, then there is oil |
| Incorrect ignition timing | Cm. Ignition system | Adjust the ignition timing |
| Low voltage circuit fault | Check with the ignition on whether voltage is supplied to the ignition coil. Use an ohmmeter to check the circuit from the ignition coil to the contacts of the breaker [K] or to the switch [B] | Clean oxidized tips, tighten loose wire fastenings, replace damaged wires, ignition switch or its contact part |
| [B] The Hall sensor or its electrical circuits are faulty | Determined by a voltmeter (see Ignition system) or replacing the sensor with a known good one | Replace the faulty sensor |
| [B] The switch is faulty | Replace the switch with a known good one | Replace the switch with a known good one |
| [K] The distributor breaker contact group is faulty: contacts are damaged or oily, the spring is weak, the moving contact is stuck on the axis | Inspection, testing with an autotester (see Ignition system) | Clean worn contacts with a file (check that they are parallel and that there is no offset) and wipe dry. If the spring is weakened, the contacts are jammed or heavily worn, replace the contact group |
| [K] Reduced capacity of the capacitor or poor contact in its circuit | Check the circuit with an autotester. To check the capacitor, remove the central wire from the ignition distributor and secure its tip at a distance of 5-6 mm from the vehicle's "ground". Turn on the ignition and manually open the breaker contacts (slightly turning it by the runner). If a strong, clicking blue spark jumps between the wire and the "ground", the capacitor is in good condition. If the spark is weak, thread-like or absent altogether, short-circuit the contacts with a piece of wire or a screwdriver. In this case, an increase in the spark will indicate a capacitor malfunction | If you suspect a capacitor is faulty, replace it |
| Weakening or breakage of the springs of the centrifugal regulator weights of the ignition distributor, loss of damper rings of the weights, jamming of the weights | Visually and on a special stand [STO] | Replace the ignition distributor |
| Vacuum advance regulator operation is fuzzy: when vacuum is removed, the plate does not return to its original position, large play in the bearing | Inspection. The vacuum regulator characteristics are taken on a special stand [STO] | Fix the jam, replace the faulty vacuum regulator or distributor assembly |
| The gap between the spark plug electrodes is not within the norm | The gap of 0.5–0.6 mm [K] (0.7–0.8 mm [B]) is checked with a round feeler gauge | By bending the side electrode, set the required gap or replace the spark plugs |
| Heavy carbon deposits on spark plug electrodes; carbon particles getting into the gap between the electrodes | Inspection | Clean the spark plugs with compressed air or mechanically (do not damage the insulator!), make sure they are in working order [STO](the absence of external damage and sparking between the electrodes on the removed spark plug does not allow us to conclude that it is in working order). Identify and eliminate the cause of increased carbon formation in the combustion chamber, replace the spark plugs if necessary |
| Defective spark plugs: current leakage through cracks in the insulator or carbon deposits on the thermal cone, poor contact in the central electrode assembly | Replace the spark plugs with known good ones or check them on a special stand [service station]. (The absence of external damage and sparking between the electrodes on the removed spark plug do not allow us to draw a conclusion about its functionality.) | Replace faulty spark plugs |
| Wear, damage to the contact carbon in the ignition distributor cap. The carbon spring is weakened | Inspection | Replace the distributor cap or the carbon with the spring |
| Burnout of high-voltage circuit insulation | Checked with an ohmmeter and visually (black cracks, insulation melting). To check high-voltage wires, replace them with known good ones | Replace faulty distributor cap, rotor, ignition coil, high-voltage wires |
| Incomplete throttle opening | Determined visually with the engine stopped | Adjust the throttle actuator |
| The valve timing is out of order | Check that the marks on the crankshaft and camshaft match (see Engine) | Set the correct relative position of the shafts (using marks) |
| Low compression in cylinders (less than 10 kgf/cm²) or its great unevenness across the cylinders (more than 2 kgf/cm²): wear or damage to valves, seats, wear, sticking or breakage of piston rings | Warm up the engine to operating temperature and remove the spark plugs. Press the gas pedal all the way down and, inserting a compression gauge into the spark plug holes, turn the crankshaft with the starter (work (more than 2 kgf/cm²): wear or damage to valves, seats, wear, sticking or breakage of piston rings | Replace rings, pistons. Repair the cylinder block [STO]. Grind the valves to the seats, if necessary, replace the valves, their guide bushings, grind the seats |
| Valve clearances not adjusted | Checked with a set of feeler gauges (See. Engine) | Adjust the gaps |
| Severe wear of camshaft lobes | Inspection after partial disassembly of the engine | Replace a worn camshaft |
| Settling or breakage of valve springs | Inspection, measurement of the length of springs in a free state and under load (after partial disassembly of the engine) | Replace weak or broken springs |
Popping noises in the intake manifold | ||
| Incorrect ignition timing | Cm. Ignition system | Adjust the ignition timing |
| The valve timing is out of order | Check that the marks on the crankshaft and camshaft match (see Engine) | Set the correct relative position of the shafts (using marks) |
Shots in the silencer | ||
| Incorrect ignition timing | Cm. Ignition system | Adjust the ignition timing |
| [K] Capacitor is faulty | Remove the central wire from the ignition distributor and secure its tip at a distance of 5-6 mm from the vehicle ground. Turn on the ignition and manually open the breaker contacts (slightly turning it by the runner). If a strong, clicking blue spark jumps between the wire and the "ground", the capacitor is in good condition. If the spark is weak, thread-like or absent altogether, short-circuit the contacts with a piece of wire or a screwdriver. In this case, an increase in the spark will indicate a capacitor malfunction | Replace the faulty capacitor |
| [B] The switch is faulty | Replace the switch with a known good one | Replace the faulty switch |
| The valve timing is out of order | Check that the marks on the crankshaft and camshaft match (see Engine) | Set the correct relative position of the shafts (using marks) |
| Burnout of high-voltage circuit insulation | Checked with an ohmmeter and visually (black cracks, insulation melting). Replace high-voltage wires for testing with known good ones | Replace faulty distributor cap, rotor, high-voltage wires |
| The ignition coil is faulty | To check, replace the coil with a known good one | Replace the faulty coil |
Popping sounds in the intake manifold after engine operation at high power levels | ||
| Spark plugs with the wrong heat rating are used | — | Use spark plugs recommended by the manufacturer |
Increased fuel consumption | ||
| Leakage in the power supply system | The smell of gasoline, streaks | Tighten the hose clamps and threaded connections. Check the fit of the fittings; if the fit becomes loose, replace the corresponding components |
| Over-enriched mixture due to gasoline leaking into the engine crankcase through a torn diaphragm in the fuel pump | The oil on the dipstick smells like gasoline, the low oil pressure indicator may light up at idle speed | Replace the fuel pump or its diaphragms; if there is a lot of gasoline in the oil, then there is oil |
| Increased resistance to vehicle movement | Coasting a warm car (after running at least 20 km) from a speed of 50 km/h there should be at least 500 m | Check and adjust tire pressure, front wheel alignment, and brake system operation |
| The carburetor starter or its drive is faulty or not adjusted | Cm. Carburetor | Adjust the starting device, replace worn parts |
| Excessive fuel level in the carburetor float chamber | There is a strong smell of gasoline coming from the exhaust pipe, a cold engine starts better than a hot one. Remove the top cover of the carburetor, check the tightness of the float, ease of movement and absence of contact with the walls of the float chamber. Checking the tightness of the needle valve: remove the carburetor cover and turn it upside down with the float upwards, pump gasoline with the fuel pump lever. The slightest leak of gasoline from under the needle or valve seat is unacceptable (see Carburetor) | Replace the needle valve, adjust the fuel level in the float chamber |
| The carburetor fuel jets are not tightly tightened. The air jets are clogged. The accelerator pump valve is leaking | There is a strong smell of gasoline from the exhaust pipe, a cold engine starts better than a hot one. The fuel level in the float chamber is normal (to check, remove the carburetor cover) (cm. Carburetor) | Wash with gasoline or acetone and blow out the jets; if heavily soiled, clean them with a fishing line or a needle made of soft wood. Tightly screw the jets in (do not damage the threads and the nozzle!) |
| Incorrect ignition timing | Cm. Ignition system | Adjust the ignition timing |
| [K] Misfiring: the contact group of the breaker-distributor is faulty: contacts are damaged or oily, the spring is weak, the moving contact is stuck on the axis | Inspection, testing with an autotester (see Ignition system) | Clean worn contacts with a file (check that they are parallel and that there is no offset) and wipe dry. If the spring is weakened, the contacts are jammed or heavily worn, replace the contact group |
| [K] Misfires: decreased capacitor capacity or poor contact in its circuit | Check the circuit with an autotester. To check the capacitor, remove the central wire from the ignition distributor and secure its tip at a distance of 5-6 mm from the vehicle's "ground". Turn on the ignition and manually open the breaker contacts (slightly turning it by the runner). If a strong, clicking blue spark jumps between the wire and the "ground", the capacitor is in good condition. If the spark is weak, thread-like or absent altogether, short-circuit the contacts with a piece of wire or a screwdriver. In this case, an increase in the spark will indicate a capacitor malfunction | If you suspect a capacitor is faulty, replace it |
| [B] The switch is faulty | Replace the switch with a known good one | Replace the faulty switch |
| Weakening or breakage of the springs of the centrifugal regulator weights of the ignition distributor, loss of damper rings of the weights, jamming of the weights | Visually and on a special stand [STO] | Replace the ignition distributor |
| Vacuum advance regulator operation is fuzzy: when vacuum is removed, the plate does not return to its original position | Inspection. The vacuum regulator characteristics are taken on a special stand [STO] | Fix the jam, replace the faulty vacuum regulator or distributor assembly |
| Defective spark plugs: current leakage through cracks in the insulator or carbon deposits on the thermal cone, poor contact in the central electrode assembly | Replace the spark plugs with known good ones or check them on a special stand [service station]. The absence of external damage and sparking between the electrodes on the removed spark plug do not allow us to conclude that it is working. | Replace faulty spark plugs |
| Engine idle speed adjustment is out of adjustment | Cm. Carburetor | Adjust idle speed |
| The carburetor throttle valves do not close completely | When held up to the light, a gap is visible between the throttle valve and the walls of the mixing chamber | Use the stop screws of the flaps to achieve their complete closure. The flaps should open easily, without jamming. After adjustment, fill the screws with paint |
| The carburetor flaps are mounted on skewed axles and do not close in any position of the stop screws | Inspection after removing the carburetor | Having supported the damper axes on a suitable stop (so as not to bend them), loosen the screws and, having correctly oriented the flaps, tighten them [STO](or replace the carburetor) |
| Foreign objects getting under the throttle valve or its drive | Inspection after removing the carburetor | Remove foreign object, check damper operation |
| Low compression in cylinders (less than 10 kgf/cm²) or its great unevenness across the cylinders (more than 2 kgf/cm²): wear or damage to valves, seats, wear, sticking or breakage of piston rings | Warm up the engine to operating temperature and remove the spark plugs. Press the gas pedal fully and, inserting a compression gauge into the spark plug holes, turn the crankshaft with the starter (work together). In this case, the high-voltage wire of the ignition coil should be shorted to ground. Repeat the measurements by pouring 10–15 cm³ of engine oil into the cylinders through the spark plug holes. In those cylinders where the compression has increased by more than 2 kgf/cm², the rings may be heavily worn, broken or stuck. If the compression remains below 10 kgf/cm², the valves or their seats may be worn or damaged | Replace rings, pistons. Repair the cylinder block [STO]. Grind the valves to the seats, if necessary, replace the valves, their guide bushings, grind the seats |
Increased oil consumption (more than 1 l per 1000 km) | ||
| Oil leakage through gaskets and seals: wear of sealing edges, hardening of gaskets, warping of mating surfaces | Wash the engine, then after a short run inspect the possible leak areas | Tighten the screws securing the oil pan, timing cover, and fuel pump; replace worn cuffs |
| Oil leak through gaskets and seals: clogged crankcase ventilation system | Inspection | Clean the ventilation system |
| Wear, loss of elasticity of valve stem seals. Wear of valve stems, guide bushings | Inspection of parts | Replace worn parts |
| Wear, breakage or coking (loss of mobility) piston rings. Wear of pistons, cylinders | Inspection after engine disassembly. See also "Low compression in cylinders..." | Replace rings, clean piston grooves. Replace worn pistons, bore and hone cylinders [STO] |
Insufficient oil pressure | ||
| Low oil in engine | By the oil dipstick | Add oil |
| Use of oil of inappropriate viscosity | — | Change the oil |
| Clogged oil receiver mesh | Inspection after removing the oil pan | Clean the mesh |
| Misalignment, clogging of the pressure reducing valve or weakening of its spring | Inspection after removing the oil pan | Clean the valve. Replace the faulty valve and/or spring |
| Wear of oil pump gears | Inspection (see Engine) | Replace worn gears |
| Excessive clearance between the bearings and the crankshaft journals | Determined by measuring the parts after disassembling the engine | Replace worn bearings. If necessary, replace or repair [STO]crankshaft |
| Oil dilution due to gasoline leaking into the engine crankcase through a torn fuel pump diaphragm | The oil on the dipstick smells like gasoline, the low oil pressure indicator may light up at idle speed | Replace the fuel pump or its diaphragms; if there is a lot of gasoline in the oil, then there is oil |
| The oil pressure sensor or its indicator is faulty | Checking with a pressure gauge and ohmmeter (see Control devices) | Replace the faulty sensor or indicator |
The engine gets very hot (the coolant temperature gauge needle is in the red zone) | ||
| The temperature sensor or indicator is faulty | Check the pointer and sensor with an autotester (see Control devices) | Faulty sensor, replace indicator |
| Thermostat is faulty | Cm. Checking the Thermostat | Replace the faulty thermostat |
| The coolant pump drive belt is loose, the pulleys are oily | Inspection (see Replacing the alternator drive belt) | Tighten the belt, replace if necessary. Eliminate the cause of oiling |
| Coolant pump is faulty | The pump pulley should be easy to turn by hand and should not have any play | Replace the pump |
| Low fluid in the cooling system | The fluid level is below the mark on the expansion tank | Fix leaks. Top up coolant (see "Coolant level in expansion tank drops") |
| Lots of scale in the cooling system | — | Flush the cooling system with a descaler. Dilute concentrated antifreeze with distilled water only |
| The radiator cells are dirty | Inspection | Flush the radiator with a jet of water under pressure |
| The electric fan of the cooling system does not turn on | Close the contacts of the radiator thermal switch. If the fan starts working (take care of your hands!) — the thermal switch is faulty, if not — the electrical circuits, relay or fan motor. Check if 12 V is supplied to the control and power contacts of the electric fan relay. If yes, then the relay or the electric fan motor is faulty, otherwise - the relay power supply circuit (checked with an ohmmeter) | Restore contact in electrical circuits. Replace faulty thermal switch, relay, electric motor |
| Unacceptably low octane number of gasoline | Engine operation is accompanied by distinct detonation knocks | Fill your vehicle with fuel recommended by the manufacturer |
| Lots of carbon deposits in the combustion chamber, on the piston bottoms, and valve plates | Inspection after removing the cylinder head | Eliminate the cause of carbon deposits (see "Increased fuel consumption", "Increased oil consumption"). Use oils of the recommended viscosity and, if possible, of high quality |
| Incorrect ignition timing | Cm. Ignition system | Adjust the ignition timing |
The electric fan of the engine cooling system is constantly running (even on a cold engine) | ||
| Radiator thermal switch contacts do not open | If the fan stops working when the wire is disconnected from the thermal switch, the switch is faulty | Replace the thermal switch |
| The contacts of the electric fan relay do not open | Checking with a tester | Replace the relay |
The engine takes a long time to warm up to operating temperature | ||
| Thermostat is faulty | Cm. Checking the Thermostat | Replace the faulty thermostat |
| Low air temperature (below -15°C) | — | Insulate the engine: install thermal and noise insulation of the hood, shields in front of the radiator (do not cover the entire radiator area in the fan impeller area!) |
| The electric fan of the engine cooling system is constantly running | See "The electric fan of the engine cooling system is always running (even on a cold engine)" | |
Coolant level in the expansion tank has dropped | ||
| Damage to the radiator, hoses, weakening of their fit on the pipes. Leakage of liquid from the heater tap | Inspection. Tightness of radiators (engine and heater) tested in a hot water bath with compressed air under a pressure of 1 kgf/cm² | Replace damaged parts. Tighten hose clamps |
| Liquid leakage through the coolant pump sleeve | Inspection | Replace the pump |
| Evaporation of liquid from the cooling system due to leaky radiator cap valves | With the engine stopped, squeeze the cooling system hoses with your hands. No liquid should flow into the expansion tank (the level should not increase) | Replace the lid |
| Damaged cylinder head gasket. Block or cylinder head defective | When changing the oil, a whitish emulsion flows out of the crankcase. Abundant white smoke from the muffler and oil stains on the surface of the liquid may appear (in the expansion tank). Coolant leaks on the outer surface of the engine | Replace damaged parts. Check the flatness of the mating surfaces of the cylinder block and head |
Detonation (high-pitched metallic knocks that usually occur when the engine is running under load, especially at low revs – acceleration "under tension", etc. – and disappear when the load is reduced) | ||
| Unacceptably low octane number of gasoline | — | Fill your vehicle with fuel recommended by the manufacturer |
| Incorrect ignition timing | Cm. Ignition system | Adjust the ignition timing |
| Engine overheating | According to the temperature indicator | Eliminate the cause of overheating (see "Engine overheats") |
| Lots of carbon deposits in the combustion chamber, on the piston bottoms, and valve plates | Inspection after removing the cylinder head | Eliminate the cause of carbon deposits (see "Increased fuel consumption", "Increased oil consumption"). Use oils of the recommended viscosity and, if possible, high quality |
| Spark plugs with the wrong heat rating are used | — | Use spark plugs recommended by the manufacturer |
Extraneous noises and knocks in the engine (except detonation, see above) | ||
| Increased clearances in the valve mechanism | Clunking noise in the cylinder head area. Measure the gaps with a feeler gauge | Adjust the gaps |
| Timing chain noise: its tension is not adjusted, the tensioner and/or damper is broken | Uniform noise in the front part of the engine. It increases at medium speeds and variable loads (it is clearly audible when releasing the "gas" from 2000-2500 min⁻¹ to 1000-1500 min⁻¹) | Tighten the chain (see Engine). If necessary, replace the chain, tensioner, and damper |
| The valve spring is broken | Uneven weak knocking in the cylinder head area. Inspection after partial disassembly of the engine | Replace the spring |
| Increased clearance between valve stem and guide bushing | Knock of medium strength and height in the cylinder head area. Play is felt when swinging a loosely inserted bushing (dried out) valves | Replace the valve, bushing |
| The camshaft lobes are severely worn (cut) | The knocking is the same as with increased clearances in the valve mechanism (see above), but cannot be eliminated by adjusting the clearances. Inspection after partial disassembly of the engine | Replace worn parts |
| Knocking of the crankshaft and camshaft, connecting rod bearings, pistons, piston pins, play or seizure in the coolant pump bearings | Check at the service station | Repair of parts at a service station or replacement of units and assemblies |
Severe engine vibration See also "Engine runs rough or stalls at idle" | ||
| The powertrain mounts have lost their elasticity or have been destroyed | Inspection | Replace the supports |
Increased content of harmful substances in exhaust gases | ||
| Excessive fuel level in the carburetor float chamber | There is a strong smell of gasoline coming from the exhaust pipe, a cold engine starts better than a hot one. Remove the top cover of the carburetor, check the tightness of the float, ease of movement and absence of contact with the walls of the float chamber. Checking the tightness of the needle valve: remove the carburetor cover and turn it upside down with the float upwards, pump gasoline with the fuel pump lever. The slightest leak of gasoline from under the needle or valve seat is unacceptable (see Carburetor) | Replace the needle valve, adjust the fuel level in the float chamber |
| Over-enriched mixture due to gasoline leaking into the engine crankcase through a torn diaphragm in the fuel pump | The oil on the dipstick smells like gasoline, and the low oil pressure indicator may light up at idle speed | Replace the fuel pump or its diaphragms; if there is a lot of gasoline in the oil, then there is oil |
| The starting device or its drive is faulty or not adjusted | Cm. Carburetor | Adjust the starting device, replace worn parts |
| Engine idle speed adjustment is out of adjustment | Cm. Carburetor | Adjust idle speed |
| The fuel jets of the carburetor are not tightly screwed in. The air jets are clogged. The accelerator pump valve is not tight | There is a strong smell of gasoline coming from the exhaust pipe, the cold engine starts better than the hot one. The fuel level in the float chamber is normal (to check, remove the carburetor cover) (cm. Carburetor) | Wash with gasoline or acetone and blow out the jets; if heavily soiled, clean them with a fishing line or a needle made of soft wood. Tightly screw the jets in (do not damage the threads and the nozzle!) |
| Incorrect ignition timing | Cm. Ignition system | Adjust the ignition timing |
| [K] Misfiring: the contact group of the breaker-distributor is faulty: contacts are damaged or oily, the spring is weak, the moving contact is stuck on the axis | Inspection, testing with an autotester (see Ignition system) | Clean worn contacts with a file (check that they are parallel and that there is no offset) and wipe dry. If the spring is weakened, the contacts are jammed or heavily worn, replace the contact group |
| [K] Misfires: decreased capacitor capacity or poor contact in its circuit | Check the circuit with an autotester. To check the capacitor, remove the central wire from the ignition distributor and secure its tip at a distance of 5-6 mm from the vehicle's "ground". Turn on the ignition and manually open the breaker contacts (slightly turning it by the runner). If a strong, clicking blue spark jumps between the wire and the "ground", the capacitor is working properly. If the spark is weak, thread-like or absent altogether, short-circuit the contacts with a piece of wire or a screwdriver. In this case, an increase in the spark will indicate a capacitor malfunction | If you suspect a capacitor is faulty, replace it |
| [B] The switch is faulty | Replace the switch with a known good one | Replace the faulty switch |
| Burnout of high-voltage circuit insulation | Checked with an ohmmeter and visually (black cracks, insulation melting). To check high-voltage wires, replace them with known good ones | Replace faulty distributor cap, rotor, ignition coil, high-voltage wires |
| Defective spark plugs: current leakage through cracks in the insulator or carbon deposits on the thermal cone, poor contact in the central electrode assembly | Replace the spark plugs with known good ones or check them on a special stand [service station]. (The absence of external damage and sparking between the electrodes on the removed spark plug do not allow us to conclude that it is in working order) | Replace faulty spark plugs |
| Weakening or breakage of the springs of the centrifugal regulator weights of the ignition distributor, loss of damper rings of the weights, jamming of the weights | Visually and on a special stand [STO] | Replace the ignition distributor |
| Vacuum ignition advance regulator is not working properly: when vacuum is removed, the plate does not return to its original position, large play in the bearing | Inspection. The vacuum regulator characteristics are taken on a special stand [STO] | Fix the jam, replace the faulty vacuum regulator or distributor assembly |
| Fix the jam, replace the faulty vacuum regulator or distributor assembly | When held up to the light, a gap is visible between the throttle valve and the walls of the mixing chamber | Use the stop screws of the flaps to achieve their complete closure. The flaps should open easily, without jamming. After adjustment, fill the screws with paint |
| The carburetor flaps are mounted on skewed axles and do not close in any position of the stop screws | Inspection | Having supported the damper axes on a suitable stop (so as not to bend them), loosen the screws and, having correctly oriented the flaps, tighten them [STO](or replace the carburetor or throttle body) |
| Foreign objects getting under the throttle valve or its drive parts | Inspection | Remove foreign object, check damper operation |
[K] – only for vehicles with contact ignition system
[B] – only for vehicles with contactless ignition system (was installed on some vehicles since 1988)
[STO] – it is recommended to perform the work at a service station
* – installed on engine parts