TROUBLESHOOTING
8-1
EAM20148
TROUBLESHOOTING
EAM30309
GENERAL INFORMATION
TIP
•
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)
TIP
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.
Summary of Contents for YZ250FX 2021
Page 6: ...EAM20162 YAMAHA MOTOR CORPORATION U S A YZ MOTORCYCLE LIMITED WARRANTY ...
Page 8: ......
Page 10: ...MOTORCYCLE CARE AND STORAGE 1 18 CARE 1 18 STORAGE 1 19 ...
Page 46: ...TIGHTENING TORQUES 2 15 ...
Page 80: ...ELECTRICAL SYSTEM 3 32 ...
Page 96: ...HANDLEBAR 4 14 Throttle grip free play 3 0 6 0 mm 0 12 0 24 in ...
Page 107: ...FRONT FORK 4 25 1 ...
Page 116: ...CHAIN DRIVE 4 34 ...
Page 128: ...FUEL TANK 6 3 ...
Page 148: ...SELF DIAGNOSTIC FUNCTION AND DIAGNOSTIC CODE TABLE 8 13 ...
Page 158: ...CHASSIS 9 9 ...
Page 160: ......
Page 163: ...YZ250FXM 2021 WIRING DIAGRAM BAJ 2819U 11_WD indd 1 2020 06 29 15 46 05 ...
Page 164: ...YZ250FXM 2021 WIRING DIAGRAM BAJ 2819U 11_WD indd 2 2020 06 29 15 46 06 ...