CONTENTS
FAULTY COMPONENTS
ACCESSORIES AND MISC.
SPARK PLUGS

CLEAN, OFTEN-BLISTERED INSULATOR

CONDITION(S)

• SPARK PLUG HAS CLEAN, OFTEN-BLISTERED INSULATOR AND BLUISH ELECTRODES THAT ARE BURNED
• PERHAPS ACCOMPANIED BY SMALL BLACK OR BROWN SPOTS ON INSULATOR, BUT NO DEPOSITS

POTENTIAL CAUSE(S)

CHECK THESE FIRST:

1. SPARK PLUG HEAT RANGE TOO HIGH
Install new spark plug(s) with lower heat range.

2. INCORRECT IGNITION TIMING
Have ignition timing professionally adjusted.
Install new spark plug(s).

3. LOW COOLANT LEVEL
Adjust coolant level if necessary.
Install new spark plug(s).

4. CLOGGED WATER JACKETS
Flush and clean cooling system.
Install new spark plug(s).

CHECK THESE NEXT:

5. INCORRECT FUEL/AIR MIXTURE
Have fuel/air mixture professionally adjusted.
Install new spark plug(s).

6.ENGINE OVERHEATING
Have cause of engine overheating professionally corrected.
Install new spark plug(s).

7. LOW FUEL PRESSURE
Have fuel pump or fuel pressure regulator professionally replaced.
Install new spark plug(s).

8. INFERIOR OR LOW OCTANE GASOLINE
Utilize higher quality or higher octane gasoline.
Install new spark plug(s).

CHECK THESE LAST:

9. LEAKING INTAKE MANIFOLD NEAR AFFECTED CYLINDER
Have intake manifold gasket professionally replaced.
Install new spark plug(s).

10. LOOSE SPARK PLUGS
Tighten spark plugs.
Install new spark plug(s).

11. SPARK PLUG(S) CROSS-FIRING
Separate spark plug wires.
Install new spark plug(s).

IN EVERY CASE, REPLACE YOUR SPARK PLUGS.

CONTENTS
SHINY YELLOW OR TAN COATING
DRY, SOFT, BLACK, SOOTY DEPOSITS