Spark Plug Condition

NOTE: Inspecting spark plug condition can determine whether problem is related to a specific cylinder or to all cylinders.

Wet/Carbon Is Stuck On Specific Plug:

Check for weak spark.
Check for excessive fuel injection volume.
Check for no or low compression.
Check for faulty spark plug.

Grayish White With Specific Plug:

Check for insufficient fuel injection volume.
Check for faulty spark plug.

Wet/Carbon Stuck On All Plugs:

Check for too rich air/fuel mixture.
Check for low compression.
Check for clogging in intake and exhaust systems.

Grayish White With All Plugs:

Check for too lean air/fuel mixture.