Product Manual

TP-6905 8/1560 Section 4 Scheduled Maintenance
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1
2
1. 0.9–1.0 mm (0.036–0.040 in.) gap
2. Spark plug electrodes
Figure 4-7 Spark Plug Gap Inspection
13. Use a gapping tool to gently bend the side
electrode closer to or farther from the center
electrode to set the correct gap. See Figure 4-8.
Position the side electrode directly over the center
electrode.
Note: Ensure that the spark p lug tubes are seated
before installing the spark plugs. If the tubes
were removed, reinstall them before
installing the spark plugs.
14. Reinstall the spark plug. Do not bump the electrode
against the cylinder head. Rotate the spark plug
clockwise until you feel resistance.
15. Use a torque wrench to torque each spark plug to
18 Nm (13.3 ft. lbs.). Otherwise, hand-tighten the
spark plug until you feel resistance.
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Figure 4-8 Spark Plug Gap Adjustment
16. Use a ratchet wrench to tighten an additional 1/4
turn. Do not overtighten, as doing so may strip the
threads or alter the electrode gap setting.
17. Check the spark plug wire connector in the boot for
accumulated d irt, grease, and other debris, and
clean as necessary.
18. Firmly push the spark plug boot onto the spark
plug.
19. Reconnect the generator set engine starting
battery, negative (--) lead last.
20. Reconnect the power for the battery charger.
Problem/Condition Means of Id en t ification Possible Cause/Solution
Gap-bridged spark
plug
Built-up deposits and gap between
electrodes closing.
Oil or carbon fouling. Clean and regap the spark
plug.
Oil-fouled spark plug Wet, black deposits on the insulator shell,
bore, and electrodes.
Excessive oil entering combustion chamber through
worn rings and pistons, excessive clearance
between valve guides and stems, or worn or loose
bearings. Replace the spark plug.
Carbon-fouled spark
plug
Black, dry, fluffy carbon deposits on insulator
tips, exposed shell surfaces and electrodes.
Incorrect spark plug, weak ignition, clogged air
intake, overrich fuel mixture, or excessive no-load
operation. Clean and regap the spark plug.
Lead-fouled spark plug Dark gray, black, yellow, or tan deposits; or a
glazed coating on the insulator tip.
Caused by highly leaded fuel. Replace the spark
plug.
Pre-ignition damaged
spark plug
Melted electrodes and possibly blistered
insulator. Metallic deposits on insulator
suggest internal engine damage.
Wrong type of fuel, incorrect timing or advance, too
hot a plug, burned valves, or engine overheating.
Replace the spark plug.
Overheated spark p lug White or light gray insulator with small black
or gray/brown spots with bluish (burned)
appearance on electrodes.
Engine overheating, wrong type of fuel, loose spark
plugs, too hot a plug, low fuel pressure or incorrect
ignition timing. Replace the spark plug.
Worn spark plug Severely eroded or worn electrodes. Caused by normal wear and failure to replace spark
plug at prescribed interval. Replace the spark plug.
Figure 4-9 Engine Evaluation Using Spark Plug Condition