Spark Plug: Testing and Inspection

Spark Plug Inspection:

Inspect the spark plugs for:
^ Improper gap
^ Carbon deposits
^ Cracked center electrode insulator

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

Replace the plug if the center electrode is rounded.
NOTE: Platinum-Tipped plugs are original equipment. Conventional plugs can be used, but will require service more frequently.

PLATINUM-TIPPED PLUGS
Standard Type - PFR6B-11 (NGK)
Hot Type - FR5B-11 (NGK)
Cold Type - PFR7B-11 (NGK)

CONVENTIONAL PLUGS
Standard Type - BKR6E (NGK)
Hot Type - BKR5E (NGK)
Cold Type - BKR7E (NGK)

Spark Plug Gap:

SPARK PLUG GAP
Platinum-Tipped Plug Electrode Gap:
0.039 - 0.043 in. (1.0 - 1.1 mm)
Conventional Plug Electrode Gap:
0.031 - 0.035 in. (0.8 - 0.9 mm)