Troubleshooting; Starting Failure/Hard Starting; Fuel System; Electrical System - Yamaha YXR70FX Service Manual

EBS00537
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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 check,
adjustment and replacement of parts.

STARTING FAILURE/HARD STARTING

FUEL SYSTEM

Fuel tank
• Empty
• Clogged fuel tank breather hoses
• Deteriorated or contaminated fuel
Fuel pump
• Faulty fuel pump
• Faulty fuel injection system relay

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
Ignition system
• Faulty ECU
• Faulty crankshaft position sensor
• Broken AC magneto rotor woodruff key
STARTING FAILURE/HARD STARTING

TROUBLESHOOTING

10 - 1
Throttle body
• Deteriorated or contaminated fuel
• Sucked-in air
Air filter
• Clogged air filter element
Switches and wiring
• Faulty main switch
• Broken or shorted wiring
• Faulty gear position switch
• Faulty brake light switch
Starting system
• Faulty starter motor
• Faulty starter relay
• Faulty starter clutch
Battery
• Faulty battery
Fuse(s)
• Blown, damaged or incorrect fuse
• Improperly installed fuse
TRBL
SHTG