TROUBLESHOOTING 3-11
ELECTRICAL
Complaint Symptom and possible causes Remedy
No sparking or poor
sparking
• Defective ignition coil
• Defective spark plug
• Defective CKP sensor
• Defective ECM
• Defective TO sensor
• Open-circuited wiring connections
Replace
Replace
Replace
Replace
Replace
Repair or replace
Spark plug soon
become fouled with
carbon.
• Mixture too rich
• Idling speed set too high
• Incorrect gasoline
• Dirty air cleaner elements
• Too cold spark plug
Inspect FI system
Adjust idle screw
Change
Clean or replace
Replace with hot type plug
Spark plug become
fouled too soon.
• Worn piston ring
• Worn piston or cylinder
• Excessive clearance of valve stems in valve guides
• Worn valve stem seal
Replace
Replace
Replace
Replace
Spark plug elec-
trodes overheat or
burn
• Too hot spark plug
• Overheated the engine
• Loose spark plug
• Too lean mixture
Replace with cold type plug
Tu n e u p
Retighten
Inspect FI system
Magneto does not
charge.
• Open- or short-circuited lead wires, or loose lead
connections
• Short-circuited, grounded or open charge coil
• Short-circuited or punctured regulator/rectifier
Repair or replace or
retighten
Replace
Replace
Magneto does
charge, but charg-
ing rate is below the
specification.
• Lead wires tend to get shorted or open-circuited or
loosely connected at terminals
• Grounded or open-circuited charge coil
• Defective regulator/rectifier
Repair or retighten
Replace
Replace
Magneto over-
charges
• Damaged or defective regulator/rectifier
• Poorly grounded regulator/rectifier
Replace
Clean and tighten ground
connection
Unstable charging • Lead wire insulation frayed due to vibration, result-
ing in intermittent short-circuiting
• Internally shorted magneto
• Defective regulator/rectifier
Repair or replace
Replace
Replace
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