3-2 TROUBLESHOOTING
ENGINE
Complaint
Symptom and possible causes
Remedy
Engine will not start
or is hard to start.
Compression too low
• Valve clearance out of adjustment
• Worn valve guides or poor seating of valves
• Mistiming valves
• Excessively worn piston ring
• Worn-down cylinder bore
• Poor seating of spark plug
• Broken, cracked, or damaged piston
• Defective automatic decomp.
Plug not sparking
• Fouled spark plug
• Wet spark plug
• Incorrect spark plug gap
• Defective spark plug
• Defective ignition coil/plug cap
• Defective ECM
• Defective CKP sensor
• Open-circuited wiring connections
• Defective magneto
No fuel reaching the intake manifold
• Clogged fuel filter or fuel hose
• Defective fuel pump
• Defective fuel pressure regulator
• Defective fuel injector
• Defective ECM
• Defective TO sensor
• Open-circuited wiring connections
Incorrect fuel/air mixture
• Defective fuel pump
• Defective fuel pressure regulator
• Defective TP sensor
• Defective CKP sensor
• Defective IAP sensor
• Defective IAT sensor
• Defective ECM
• Defective ECT sensor
Adjust
Repair or replace
Adjust
Replace
Replace
Retighten
Replace
Clean or replace
Clean
Clean and dry
Replace
Replace
Replace
Replace
Replace
Repair or replace
Replace
Clean or replace
Replace
Replace
Replace
Replace
Replace
Repair or replace
Replace
Replace
Replace
Replace
Replace
Replace
Replace
Replace