Yamaha YZ250 2021, Owner'S Manual

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TROUBLESHOOTING
7-1
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.
EAM30612
TROUBLESHOOTING OF ENGINE
Engine will not start or is difficult to start, but it cranks.
Symptom Possible cause Actions
Spark plug does not produce a
spark
Have a Yamaha dealer check the electrical system.
Fuel not supplied
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 cock strainer
Clean or replace the fuel cock
strainer.
Clogged fuel cock Clean or replace the fuel cock.
Cracked, damaged or worn fuel
cock
Replace the fuel cock.
Clogged carburetor fuel passage Clean the carburetor.
Clogged needle valve or needle
valve seat
Clean the needle valve or needle
valve seat.
Damaged float Replace the float.
Clogged pilot jet Clean the pilot jet.
Clogged starter jet Clean the starter jet.
Bent or damaged starter plunger Replace the starter plunger.
Incorrectly adjusted starter cable Adjust the starter cable.
—
Water or foreign material in fuel,
degraded fuel
Change fuel.