Spark Plug: Testing and Inspection

Spark Plug Inspection:

Inspect the spark plugs for:
^ Improper gap
^ Carbon deposits
^ Cracked center electrode insulator
^ Rounded center electrode
Burned or worn electrodes (may be caused by):
^ Excessive mileage
^ Lean fuel mixture
^ Advanced ignition timing
^ Loose spark plug
^ Plug heat range too high
^ Insufficient Cooling
Fouled plug (may be caused by):
^ Rich 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

Spark Plug Gap:

Adjust the gap with a suitable gapping tool.
^ Electrode Gap: 0.8-0.9 mm (0.031-0.035 in.)