Poor Running or No Power at High Speed:

Symptoms or Possible Causes

Actions (chapter)

Firing incorrect :

Spark plug dirty, broken or maladjusted

Clean spark plug and adjust plug gap (see chapter

2).

Spark plug cap trouble

Inspect stick coil (see chapter 16).

Spark plug cap shorted or not in good contact

Reinstall or inspect stick coil (see chapter 16).

Spark plug incorrect

Replace it with the correct plug (see chapter 16).

IC igniter in ECU trouble

Inspect (see chapter 16).

Crankshaft sensor trouble

Inspect (see chapter 16).

Stick coil trouble

Inspect (see chapter 16).

Fuel/air mixture incorrect :

Choke lever pulled

Push it (see chapter 3).

Air cleaner clogged, poorly sealed or missing

Clean element or inspect sealing (see chapter 3).

Air cleaner duct loose

Reinstall (see chapter 3).

Air cleaner O-ring damaged

Replace (see chapter 3).

Water or foreign matter in fuel

Change fuel. Inspect and clean fuel system (see

chapter 3).

Throttle body assy loose

Reinstall (see chapter 3).

Throttle body assy O-ring damaged

Replace (see chapter 3).

Fuel tank air vent obstructed

Inspect and repair (see chapter 3).

Fuel line clogged

Inspect and repair (see chapter 3).

Fuel pump operates intermittently and often

Pump bearings may wear. Replace the pump (see

ECU fuse blows.

chapter 3).

Fuel pump trouble

Inspect (see chapter 3).

Inlet air temperature sensor trouble

Inspect (see chapter 3).

Main throttle sensor trouble

Inspect (see chapter 3).

Atmospheric pressure sensor trouble

Inspect (see chapter 3).

Inlet air pressure sensor trouble

Inspect (see chapter 3).

Cracked or obstructed inlet air pressure sensor

Inspect and repair or replace (see chapter 3).

hose

Injector clogged

Visually inspect and replace (see chapter 3).

Compression low :

Spark plug loose

Reinstall (see chapter 16).

Cylinder head not sufficiently tightened down

Tighten (see chapter 5).

No valve clearance

Adjust (see chapter 2).

Cylinder, piston worn

Inspect and replace (see chapter 5).

Piston ring bad (worn, weak, broken or sticking)

Inspect and replace (see chapter 5).

Piston ring/groove clearance excessive

Inspect and replace (see chapter 5).

Cylinder head gasket damaged

Replace (see chapter 5) .

Cylinder head warped

Inspect and replace (see chapter 5).

Valve spring broken or weak

Inspect and replace (see chapter 5).

Valve not seating properly (valve bent , worn or

Inspect and repair or replace (see chapter 5).

carbon accumulating on the seating surface)

Knocking :

Carbon built up in combustion chamber

Repair (see chapter 5).

FUEL SYSTEM (DFI) 3-31

DFI System Troubleshooting Guide

Symptoms or Possible Causes

Actions (chapter)

Fuel poor quality or incorrect (Use the gasoline

Change fuel (see chapter 3).

recommended in the Owner’s Manual)

Spark plug incorrect

Replace it with the correct plug (see chapter 16).

Stick coil trouble

Inspect (see chapter 16).

IC igniter in ECU trouble

Inspect (see chapter 16).

Inlet air temperature sensor trouble

Inspect (see chapter 3).

Atmospheric pressure sensor trouble

Inspect (see chapter 3).

Miscellaneous :

Subthrottle sensor trouble

Inspect (see chapter 3).

Subthrottle valve actuator trouble

Inspect (see chapter 3).

Speed sensor trouble

Inspect (see chapter 3).

Throttle valves won’t fully open

Inspect throttle cable and lever linkage (see

chapter 3).

Inspect caliper fluid seal damage or clogging

Brake dragging

of master cylinder relief and supply ports (see

chapter 12).

Clutch slipping

Inspect friction plates for wear (see chapter 6).

Engine overheating - water temperature sensor,

(see Overheating of Troubleshooting Guide in

crankshaft sensor or speed sensor trouble

chapter 17).

Engine oil level too high

Repair (see chapter 7).

Engine oil viscosity too high

Change (see chapter 3).

Drive train trouble

Inspect drive chain (see chapter 2) and sprockets

(see chapter 11).

Camshaft cam worn

Inspect and replace (see chapter 5).

Vacuum switch valve trouble

Inspect and replace (see chapter 5).

Air suction valve trouble

Inspect and replace (see chapter 5).

Catalytic converters melt down due to muffler

Replace muffler (see chapter 5).

overheating (KLEEN)

Exhaust Smokes Excessively :

(White smokes)

Piston oil ring worn

Inspect and replace (see chapter 5).

Cylinder worn

Inspect and replace (see chapter 5).

Valve oil seal damaged

Replace (see chapter 5).

Valve guide worn

Replace the guide (see chapter 5).

Engine oil level too high

Repair (see chapter 7).

(Black smoke)

Air cleaner clogged

Clean (see chapter 3).

Choke lever pulled

Push it (see chapter 3).

Too high fuel pressure

Inspect (see chapter 3) .

Injector stuck open

Inspect (see chapter 3).

Water temperature sensor trouble

Inspect and replace (see chapter 3).

Inlet air temperature sensor trouble

Inspect and replace (see chapter 3).

(Brown smoke)

Air cleaner duct loose

Reinstall (see chapter 3).

Air cleaner O-ring damaged

Replace (see chapter 3).

Symptoms or Possible Causes

Actions (chapter)

Too low fuel pressure

Inspect fuel line and fuel pump (see chapter 3).

Water temperature sensor trouble

Inspect and replace (see chapter 3).

Inlet air temperature sensor trouble

Inspect and replace (see chapter 3).