TP-6903 5/16a Fuel System Troubleshooting 51
3.5. Cuts Out and Misses
Definition: A surging or jerking that follows engine
speed, usually more pronounced as the engine load
increases, but normally felt below 1500 rpm. The
exhaust has a steady spitting sound at low speed or
hard acceleration resulting from fuel starvation that can
cause the engine to cut-out.
Figure 3-7 Cuts Out or Misses Troubleshooting
Checks Action
Preliminary Checks None
Ignition System Checks
Start the engine.
Check for proper ignition output voltage with a spark tester.
Check for a cylinder misfire.
Verify that the spark plugs are the correct type and properly gapped.
Remove the spark plugs and check for the following conditions:
o Insulation cracks.
o Wear.
o Improper gap.
o Burned electrodes.
o Heavy deposits.
Visually/physically inspect the ignition for the following:
o Ignition leads for arcing and proper routing.
o Cross-firing.
o Ignition coils for cracks or carbon tracking.
Engine Mechanical Checks
Perform a cylinder compression check. Check the engine for the following:
o Improper valve timing.
o Improper valve clearance.
o Worn rocker arms.
o Worn camshaft lobes.
o Broken or weak valve springs.
o Check the intake and exhaust manifold passages for casting flash.
Fuel System Checks
Check the fuel system for:
o Plugged fuel filter (if equipped).
o Low fuel pressure.
o Check the condition of the wiring to the shut-off valves.
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