Due to the fault of the ignition system, the engine may not start for the following reasons:
- open or short circuit in the low voltage circuit;
- malfunction of candles, distributor, coil or ignition switch;
- incorrect connection of wires to candles;
- pollution or breakage of high-voltage wires;
- incorrect ignition timing;
- damage to the slider and distributor cap.
Unstable operation of the engine at idle can be caused by an increased gap between the electrodes of the spark plugs or incorrectly set ignition timing.
The reasons due to which the engine is unstable in all modes may be damage or unreliable connection of high-voltage wires, oiling or malfunction of candles, malfunction of the switch, slider or distributor cap.
The reason why the engine is unstable at high speeds may be a malfunction of the ignition distributor.
The engine does not develop full power due to a malfunction of the ignition switch or distributor, or incorrect ignition timing.
Attention! The ignition switch generates a large amount of heat during operation.
Warning! In order not to damage the electronic devices of the ignition system, as well as to avoid possible personal injury, follow these rules:
1. Do not touch high-voltage wires and system nodes with your hands (coil, commutator, etc.) when the engine is running, since the non-contact ignition system has a higher voltage compared to the contact system.
2. Don't test the system "for a spark", holding the tip of a candle or a high-voltage wire in your hands. To check, use a special spark gap.
3. It is forbidden to lay low and high voltage wires of the ignition system in the same bundle.
4. Do not disconnect the wires from the battery terminals with the ignition on: this will damage the electronic components of the ignition system.
5. It is forbidden to disconnect the block with wires from the switch when the ignition is on: the switch will fail.
6. Be careful not to loosen the screws securing the switch: these screws connect it to the "weight".
Attention! During the test, do not touch the wires and devices of the ignition system with the engine running.
Attention! Disconnect and connect wires of system of ignition only at the switched off ignition.
Attention! To check for "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, electronic devices of the ignition system may fail. As a spark gap, you can use old workable candles. The gap between the electrodes of the candles should be 0.7–0.8 mm.
Malfunctions in the ignition system lead to unstable operation of the engine, and problems with starting are also possible.
Before troubleshooting the ignition system, make sure the fuel system is working. If gasoline does not enter the carburetor, the engine will not start. To check, remove the hose from the carburetor coming from the fuel pump and pump fuel with the manual priming lever, while fuel should splash out of the hose. The engine may run rough due to a high level of fuel in the carburetor float chamber, a faulty brake booster, or a leaky connection between the booster vacuum hose and the engine intake pipe or booster check valve.
Causes of unstable engine operation:
1. Dirty or damaged high voltage wires. This is especially evident in damp rainy weather.
2. High-voltage wires are not fully inserted into the sockets of the ignition distributor cover or ignition coil, as well as into the tips of the candles.
3. The spark plugs are faulty or the gaps between the spark plug electrodes are not adjusted.
4. Ignition timing incorrectly adjusted.
5. Malfunction of the slider or its resistor.
6. Ignition distributor cover damage (especially manifested in wet and rainy weather).
7. Ignition switch malfunction.
8. Faulty ignition coil.
Periodically clean high-voltage wires, spark plug tips, ignition coil, distributor cap and switch with base from dust and dirt.
Engine won't start
1. Check if voltage is applied to the spark plugs. To do this, remove the high-voltage wire from the central socket of the distributor cover and connect it to the arrester. Turn on the starter for a few seconds, while a spark should periodically jump between the electrodes of the arrester. If there is no spark, then no voltage is applied to the candles. If there is a spark, check the operation of the candles in the same way, removing the tips with wires from them one by one. If any spark plug does not have a spark, replace its wire. If there is a spark on all wires, and the engine does not start, replace the candles.
2. If voltage is not applied to the spark plugs (no spark on all four plugs), replace the distributor slider. Sometimes the runner resistor fails. You can check its performance with an ohmmeter: the resistance of the resistor should be 0.9–1.1 kOhm. If the resistance is not as specified, replace the slider. If, after replacing the slider, voltage is not supplied to the candles, replace the ignition distributor cap. If after this the engine does not start, replace the ignition coil, switch and ignition distributor in sequence.
Engine running erratically
1. Clean the high voltage wires and check their condition. Damage to the insulation of high-voltage wires and the cover of the ignition distributor 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 of the candles is faulty, disconnect the wire from it with the engine off, then start the engine. If interruptions in the operation of the engine have increased, then the candle is working. After that, 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 nature of the vibrations has not changed, this candle is faulty and must 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 erratically, replace the slider and distributor cap.
4. If after replacing the cap and runner, engine misfires continue, replace the ignition switch.
5. If after this the nature of the engine has not changed, check the ignition timing or contact a car service.