- Engine cranks, but won't start:
Spark is insufficient or does not occur at all, at spark plug:
Check ignition coil.
Spark is good:
Check the ignition timing.
- Engine Idles Roughly or Stalls:
- Poor Acceleration:
- Engine overheats or consumes excessive fuel:
SECONDARY SPARK TEST
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 a good ground on the engine.
- Crank the engine and check for spark at the tester.
- If spark exists at the tester, the ignition system is functioning properly.
- If spark does not exist at the spark plug wire, remove the distributor cap and ensure the rotor is turning when the engine is cranked.
- If the rotor is turning, perform the spark test again using the ignition coil wire.
- If spark does not exist at the ignition coil wire, test the ignition coil, power transistor and related wiring. Repair or replace components as necessary.