Spark Plug: Testing and Inspection

Spark Plug Chart:

1. Inspect the spark plugs for:
^ Electrode gap (refer to SPECIFICATIONS)
^ Carbon deposits
^ Cracked center electrode insulator
^ Burned or worn electrodes (may be caused by):
^ Excessive mileage
^ Lean air/fuel mixture
^ Advanced ignition timing
^ Loose spark plug
^ Plug heat range too high
^ Insufficient Cooling
^ Fouled plug (may be caused by):
^ Rich air/fuel mixture
^ Retarded ignition timing
^ Oil in combustion chamber
^ Incorrect spark plug gap
^ Plug heat range too low
^ Excessive idling/low speed running
^ Clogged air cleaner element
^ Deteriorated ignition coil, coil wire or ignition wires

2. Replace the plug if the center electrode is rounded.