Troubleshooting; Starting Failure/Hard Starting; Electrical System - Yamaha YFM660FP Service Manual

NOTE:
The following troubleshooting does not cover all the possible causes of trouble. It should be helpful,
however, as a guide to troubleshooting. Refer to the relative procedure in this manual for inspection,
adjustment and replacement of parts.

STARTING FAILURE/HARD STARTING

FUEL SYSTEM
Fuel tank
Empty
●
Clogged fuel filter
●
Clogged fuel strainer
●
Clogged fuel breather hose
●
Deteriorated or contaminated fuel
●
Fuel cock
Clogged fuel hose
●

ELECTRICAL SYSTEM

Spark plug
Improper plug gap
●
Worn electrodes
●
Wire between terminals broken
●
Improper heat range
●
Faulty spark plug cap
●
Ignition coil
Broken or shorted primary/secondary
●
Faulty spark plug lead
●
Broken body
●
CDI system
Faulty CDI unit
●
Faulty pickup coil
●
Faulty charging/rotor rotation direction coil
●
Broken woodruff key
●
STARTING FAILURE/HARD STARTING

TROUBLESHOOTING

10 - 1
Carburetor
Deteriorated or contaminated fuel
●
Clogged pilot jet
●
Clogged pilot air passage
●
Sucked-in air
●
Deformed float
●
Worn needle valve
●
Improperly sealed valve seat
●
Improperly adjusted fuel level
●
Improperly set pilot jet
●
Clogged starter jet
●
Starter plunger malfunction
●
Air filter
Clogged air filter element
●
Switches and wiring
Faulty main switch
●
Faulty engine stop switch
●
Broken or shorted wiring
●
Faulty gear position switch
●
Faulty start switch
●
Faulty rear brake switch
●
Starter motor
Faulty starter motor
●
Faulty starter relay
●
Faulty starter clutch
●
TRBL
SHTG
10