Yamaha YZ450FX 2023, Owner'S Manual

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TROUBLESHOOTING
8-1
EAM20148
TROUBLESHOOTING
EAM30309
GENERAL INFORMATION
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• Troubleshooting information provided here does not cover all the trouble symptoms, possible causes,
and remedial actions. Some items may not apply depending on the model. Use this information as a
guide and quick reference matrix when performing basic troubleshooting. Refer to the each chapter
for detailed information on checking, adjustment, and replacement.
• The following guide for troubleshooting represent quick and easy procedures for checking these vital
systems yourself. However, should your motorcycle require any repair, take it to a Yamaha dealer,
whose skilled technicians have the necessary tools, experience, and know-how to service the motor-
cycle properly.
EAM30509
TROUBLESHOOTING OF ENGINE (fault code not detected)
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If a fault code is detected, have a Yamaha dealer check the electrical system.
Engine does not crank.
Engine will not start or is difficult to start, but it cranks.
Symptom Possible cause Actions
Starter motor does not operate Have a Yamaha dealer check the electrical system.
Starter motor operates, but the
engine does not crank.
Starter clutch malfunction Replace the starter clutch.
Improper oil grade (starter clutch
slipping)
Change to recommended engine
oil.
Stuck piston or seized crankshaft
Disassemble and check the
engine. Replace defective parts.
Symptom Possible cause Actions
Spark plug does not produce a
spark
Have a Yamaha dealer check the electrical system.
Fuel not supplied
— Measure the fuel pressure.
Empty fuel tank Fill the fuel tank with fuel.
Clogged fuel tank cap breather
hole
Clean the fuel tank cap.
Clogged or damaged fuel hose
Clean, repair, or replace the fuel
hose.
Fuel leakage
Check the fuel passage. Repair or
replace as necessary.
Clogged fuel pump Clean or replace the fuel pump.
Cracks or damage in fuel pump Replace the fuel pump.
Fuel pump malfunction
Have a Yamaha dealer check the
electrical system.
Failed or clogged fuel injector Replace the fuel injector.
ECU failure Replace the ECU.