2009 Suzuki 400 LTZ Quad Sport Service Manual, Page 253Get this manual
1H-2 Ignition System:
Diagnostic Information and Procedures
Ignition System Symptom Diagnosis
Condition Spark plug not sparking Possible cause Damaged spark plug capDamaged spark plugFouled spark plugWet spark plugDefective ignition coilDefective CKP sensorDefective ECMOpen-circuited wiring connectionsOpen or short in high-tension cordDefective ignition coilFouled spark plugDefective CKP sensorDefective ECMOpen-circuited wiring connectionsExcessively rich airfuel mixtureExcessively high idling speedIncorrect gasolineDirty air cleaner elementIncorrect spark plug(Cold type) Worn piston ringsWorn pistonWorn cylinderExcessive valve-stem to valve-guide clearanceWorn valve stem oil sealsIncorrect spark plugOverheated engineLoose spark plugExcessively lean airfuel mixtureB933H21804001