Due to the fault of the ignition system, the engine may not start for the following reasons:
- open or short circuit in low voltage circuit;
- malfunction of spark plugs, distributor, coil or ignition switch;
- incorrect connection of wires to spark plugs;
- contamination or breakage of high-voltage wires;
- incorrect ignition timing;
- damage to the rotor and distributor cap.
Unstable engine operation at idle may be caused by an increased gap between the spark plug electrodes or incorrect ignition timing.
The reasons why the engine operates unstably in all modes may be damage or unreliable connection of high-voltage wires, oily or faulty spark plugs, faulty commutator, rotor or distributor cap.
The reason why the engine runs unsteadily at high speeds may be a faulty ignition distributor.
The engine does not develop full power due to a faulty ignition switch or distributor, or incorrect ignition timing.
Caution! When the ignition switch is in operation, a large amount of heat is generated.
Warning! To avoid damaging the electronic devices of the ignition system and to avoid possible injuries, follow these rules:
1. Do not touch high-voltage wires and system components with your hands (coils, commutators, etc.) when the engine is running, since the contactless ignition system has a higher voltage compared to the contact system.
2. Do not check the system's functionality "by sparking" by holding the spark plug tip or high-voltage wire in your hands. Use a special spark gap for checking.
3. It is prohibited to lay low and high voltage wires of the ignition system in the same harness.
4. Do not disconnect the wires from the battery terminals when the ignition is on: this will damage the electronic components of the ignition system.
5. It is prohibited to disconnect the connector with wires from the switch when the ignition is on: the switch will fail.
6. Do not allow the screws that secure the switch to loosen: these screws connect it to the ground.
Caution! During the inspection, do not touch the wires and devices of the ignition system when the engine is running.
Caution! Disconnect and connect ignition system wires only when the ignition is off.
Attention! To check for a "spark", you need to use a special spark gap with a gap between the electrodes of 5-7 mm. If the gap is more than 10 mm, the electronic devices of the ignition system may fail. Old working spark plugs can be used as a spark gap. The gap between the spark plug electrodes should be 0.7-0.8 mm.
Malfunctions in the ignition system lead to unstable engine operation, and problems with starting are also possible.
Before you start troubleshooting the ignition system, make sure the fuel system is working properly. If gasoline is not getting to the carburetor, the engine will not start. To check, remove the hose from the carburetor that goes from the fuel pump and pump fuel using the hand pump lever; fuel should splash out of the hose. The engine may run intermittently due to a high fuel level in the carburetor float chamber, a faulty brake booster, or a leaky connection between the booster vacuum hose and the engine intake pipe or the booster check valve.
Reasons for unstable engine operation:
1. Dirty or damaged high-voltage wires. This is especially evident in damp, rainy weather.
2. The high-voltage wires are not fully inserted into the sockets of the distributor cap or ignition coil, or into the spark plug tips.
3. The spark plugs are faulty or the gaps between the spark plug electrodes are not adjusted.
4. The ignition timing angle is not adjusted correctly.
5. The runner or its resistor is faulty.
6. Damage to the ignition distributor cap (especially evident in damp and rainy weather).
7. Ignition switch malfunction.
8. Ignition coil failure.
Periodically clean dust and dirt from high-voltage wires, spark plug tips, ignition coil, distributor cap and commutator with base.
The engine does not start
1. Check if voltage is supplied to the spark plugs. To do this, remove the high-voltage wire from the central socket of the distributor cap and connect it to the spark gap. Turn on the starter for a few seconds; a spark should periodically jump between the electrodes of the spark gap. If there is no spark, then voltage is not supplied to the spark plugs. If there is a spark, check the operation of the spark plugs in the same way, removing the tips with wires from them one by one. If there is no spark on any spark plug, replace its wire. If there is a spark on all wires, but the engine does not start, replace the spark plugs.
2. If voltage is not supplied to the spark plugs (no spark on all four spark plugs), replace the distributor rotor. Sometimes the rotor resistor fails. You can check its functionality using an ohmmeter: the resistor resistance should be 0.9–1.1 kOhm. If the resistance differs from the specified value, replace the rotor. If after replacing the rotor there is no voltage supplied to the spark plugs, replace the distributor cap. If the engine does not start after this, replace the ignition coil, switch and distributor in sequence.
The engine runs erratically
1. Clean the high-voltage wires and check their condition. Damage to the insulation of the high-voltage wires and the distributor cap can be determined in the dark. To do this, start the engine and inspect the engine compartment. A characteristic glow will be visible in the damaged area.
2. To determine which spark plug is faulty, disconnect the wire from it with the engine off, then start the engine. If the engine misfires more, then the spark plug is OK. Then stop the engine and connect the wire to the spark plug. Remove the wire from the other spark plug and start the engine again. If the vibration pattern does not change, this spark plug is faulty and should be replaced. If the engine continues to run intermittently, replace the spark plug wire.
3. If all spark plugs and wires are good and the engine continues to run rough, replace the rotor and distributor cap.
4. If the engine continues to misfire after replacing the cap and rotor, replace the ignition switch.
5. If after this the engine operation has not changed, check the ignition timing or contact a car service center.