3-32 FUEL SYSTEM (DFI)
DFI System Troubleshooting Guide
Symptoms or Possible Causes
Incorrect idle speed:
Water temperature sensor trouble
Main throttle sensor trouble
Engine stalls easily:
Fuel pump trouble
Fuel injector trouble
Main throttle sensor trouble
Camshaft position sensor trouble
Fuel pressure too low or too high
Inlet air pressure sensor trouble
Water temperature sensor trouble
Inlet air temperature sensor trouble
Fuel line clogged
Fuel pressure too low or too high
Fuel pressure regulator trouble
Crankshaft sensor trouble
Stick coil trouble
Compression Low:
Spark plug loose
Cylinder head not sufficiently tightened down
No valve clearance
Cylinder, piston worn
Piston ring bad (worn, weak, broken or sticking ) Inspect and replace (see chapter 5).
Piston ring/groove clearance excessive
Cylinder head gasket damaged
Cylinder head warped
Valve guide worn or stem seal damaged
Valve spring broken or weak
Valve not seating properly (valve bent, worn or
carbon accumulating on seating surface)
Camshaft cam worn
Hesitation:
Too low fuel pressure
Clogged fuel line
Cracked or obstructed inlet air pressure sensor
hose
Fuel pump trouble
Fuel injector trouble
Inlet air temperature sensor trouble
Main throttle sensor trouble
Subthrottle sensor trouble
Subthrottle valve actuator trouble
Water temperature sensor trouble
Atmospheric pressure sensor trouble
Actions
Inspect (see chapter 3).
Inspect (see chapter 3).
Inspect (see chapter 3).
Inspect (see chapter 3).
Inspect (see chapter 3).
Inspect (see chapter 3).
Inspect (see chapter 3).
Inspect (see chapter 3).
Inspect (see chapter 3).
Inspect (see chapter 3).
Inspect and repair (see chapter 3).
Inspect (see chapter 3).
Inspect fuel pressure and replace fuel pump (see
chapter 3).
Inspect (see chapter 16).
Inspect (see chapter 16).
Reinstall (see chapter 16).
Tighten (see chapter 5).
Adjust (see chapter 2).
Inspect and replace (see chapter 5).
Inspect and replace (see chapter 5).
Replace (see chapter 5).
Inspect and replace (see chapter 5).
Inspect and replace (see chapter 5).
Inspect and replace (see chapter 5).
Inspect and repair or replace (see chapter 5).
Inspect and replace (see chapter 5).
Inspect (see chapter 3).
Inspect and repair (see chapter 3).
Inspect and repair or replace (see chapter 3).
Inspect (see chapter 3).
Inspect (see chapter 3).
Inspect (see chapter 3).
Inspect (see chapter 3).
Inspect (see chapter 3).
Inspect (see chapter 3).
Inspect (see chapter 3).
Inspect (see chapter 3).
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