Spark Plug: Testing and Inspection

SPARK PLUG TEST
1. Remove the spark plug from the engine and connect it to the spark plug cable boot.
2. Ground the spark plug outer electrode (body), and crank the engine. Check for spark across the electrodes.
3. Remove the spark plug from the boot and visually inspect it for cracks in its insulation.
4. Replace the spark plug if it has a weak spark and/or detective insulation.

SPARK PLUG CHECK AND CLEANING
1. Remove the spark plug cables.

CAUTION: When pulling the spark plug cable boot from the plug, always hold the boot, not the cable.

2. Remove the spark plugs.
3. Check for a burned-out electrode or damaged insulator. Check for even burning.




4. Remove carbon deposits with wire brush or plug cleaner. Remove sand from plug screw with compressed air.
5. Use a gap gauge to check the plug gap.
Standard value: 1.22 - 1.35 mm (0.048 - 0.053 in.)
If the plug gap is not within the standard value range, adjust by bending the ground electrode.
6. Clean the engine plug holes.

CAUTION: Do not allow foreign matter to enter the cylinders.

7. Install the spark plugs.