Before performing any component testing, check for and, if necessary, repair the following:
SECONDARY SPARK TEST
See Figure 1
The best way to perform this procedure is to use a spark tester (available at most automotive parts stores). Two types of spark testers are commonly available. The neon bulb type is connected to the spark plug wire and flashes with each ignition pulse. The air gap type must be adjusted to the individual spark plug gap specified for the engine. This type of tester allows the user to not only detect the presence of spark, but also the intensity (orange/yellow is weak, blue is strong).
- Disconnect a spark plug wire at the spark plug end.
- Connect the plug wire to the spark tester and ground the tester to an appropriate location on the engine.
- Crank the engine and check for spark at the tester.
- If a spark did occur, inspect the distributor cap, adapter, rotor for cracks, carbon tracking, or lack of silicone compound. Also, check that the roll pin is securing the armature to the sleeve in the distributor.
- If spark does not exist at the spark plug wire, remove the distributor cap and ensure that the rotor is turning when the engine is cranked.
If no spark occurs, check the following:
- Using a Digital Volt Ohmmeter (DVOM), measure the resistance of the ignition coil secondary wire (high voltage wire). The reading should not exceed 5,000 ohms per foot.
- Inspect the ignition coil for damage or carbon tracking.
- Also, check that the distributor shaft is rotating while the engine is being cranked.
- If no spark occurs, go to the module voltage test in this section.
See Figure 2
- Turn the ignition switch OFF .
- Measure the battery voltage.
Do not allow the straight pin to contact electrical ground, while performing this test.
- Carefully insert a small straight pin in the RED module wire.
- Attach the negative lead of a Digital Volt Ohmmeter (DVOM) to the distributor base.
- Attach the positive lead of the DVOM to the straight pin and measure the voltage, with the ignition switch in RUN position.
- Turn the ignition switch OFF and remove the straight pin.
- If the results are within 90% of battery voltage, go to the ballast resistor test in this section.
- If the results are not within 90% of battery voltage, inspect the wiring harness between the module and ignition switch. Also, check for a faulty ignition switch.
See Figure 3
- Unplug and inspect the ignition module 2-wire connector (RED and WHITE).
- Unplug and inspect the ignition coil connector.
- Using a Digital Volt Ohmmeter (DVOM), measure the ballast resistor resistance between the battery terminal of the ignition coil connector and the wiring harness connector mating with the RED module wire. The results should be between 0.6-1.6 ohms.
- If the result is less than 0.6 ohms, or greater than 1.6 ohms, replace the ballast resistor.
- If the result is okay, the problem is either intermittent or not in the ignition system.