Spark Plug: Testing and Inspection

CAUTION: Do not attempt any maintenance on spark plugs if engine is hot.

Inspection
1. Reconnect negative battery cable.
2. Connect spark plug to high-tension lead.
3. Hold spark plug with insulated pliers 0.2 to 0.39 inch (5 - 10 mm) from a ground.

WARNING: Do not touch vehicle body during following instructions.




4. While holding spark plug, have a second person crank engine. Verify that a strong blue spark jumps from spark plug to ground.




5. If there is no spark or the spark is weak, check for, and implement correction:
- Carbon deposits. Clean out or replace plug.
- Oil fouling. Correct oil problem, replace plug.
- Worn or burnt electrode. If present, replace plug.
- Broken or burned ceramic insulator. If present replace plug.
- Damaged spark plug ring. If so, replace ring.
- Improper spark plug gap. Regap if possible, otherwise replace plug.

Gap: 0.027 - 0.031 inch (0.1 - 0.8 mm)