3-32 FUEL SYSTEM (DFI)
DFI System Troubleshooting Guide
Symptoms or possible Causes
Cylinder head warped
No valve clearance
Valve guide worn
Valve spring broken or weak
Valve not seating properly (valve bent, worn or
carbon accumulating on seating surface)
Poor Running at Low Speed
Symptoms or Possible Causes
Spark weak:
Battery voltage low
Spark plug dirty, broken or gap maladjusted
Spark plug cap trouble
Spark plug cap shorted or not in good contact
Spark plug incorrect
IC igniter in ECU trouble
Crankshaft sensor trouble
Stick coil trouble
Fuel/air mixture incorrect:
Little fuel in tank
Air cleaner clogged, poorly sealed, or missing
Air cleaner duct loose
Air cleaner O-ring damaged
Fuel tank air vent obstructed
Throttle body assy loose
Throttle body assy O-ring damage
Fuel filter or pump screen clogged
Fuel pressure regulator clogged
Fuel line clogged
Inlet air pressure sensor trouble
Inlet air temperature sensor trouble
Thermostat trouble
Unstable (rough) idling:
Fuel injector trouble
Main throttle sensor trouble
Crankshaft sensor trouble
Throttle valves not synchronizing
Inlet air temperature sensor trouble
Water temperature sensor trouble
Atmospheric pressure sensor trouble
Fuel pressure too low or too high
Battery voltage low
Actions
Inspect and replace (see chapter 5).
Adjust (see chapter 2).
Inspect and replace (see chapter 5).
Inspect and replace (see chapter 5).
Inspect and repair or replace (see chapter 5).
Actions
Inspect and charge (see chapter 16).
Replace (see chapter 2).
Inspect the stick coil (see chapter 16).
Reinstall or inspect stick coil (see chapter 16).
Replace it with the correct plug (see chapter 16).
Inspect (see chapter 16).
Inspect (see chapter 16).
Inspect (see chapter 16).
Supply fuel (see Owner's Manual).
Clean element or inspect sealing (see chapter
2, 3).
Reinstall (see chapter 3).
Replace (see chapter 3).
Inspect and repair (see chapter 3).
Reinstall (see chapter 3).
Replace (see chapter 3).
Inspect and replace fuel pump (see chapter 3).
Inspect fuel pressure and replace fuel pump (see
chapter 3).
Inspect and repair (see chapter 3).
Inspect (see chapter 3).
Inspect (see chapter 3).
Inspect and replace (see chapter 4).
Inspect (see chapter 3).
Inspect (see chapter 3).
Inspect (see chapter 3).
Inspect (see chapter 2).
Inspect (see chapter 3).
Inspect (see chapter 3).
Inspect (see chapter 3).
Inspect (see chapter 3).
Inspect and charge (see chapter 16).
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