Yamaha YZ250FM 2021 Owner's Service Manual

TROUBLESHOOTING9-1EAM20148TROUBLESHOOTINGEAM30309GENERAL INFORMATIONTIPTroubleshooting 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 aguide and quick reference matrix when performing basic troubleshooting. Refer to the each chapter fordetailed information on checking, adjustment, and replacement.EAM30509TROUBLESHOOTING OF ENGINE (fault code not detected)TIPIf a fault code is detected, refer to the “FUEL INJECTION SYSTEM” on page 8-13.Engine does not crank.Engine will not start or is difficult to start, but it cranks.Symptom Possible cause ActionsStarter motor does not operate Refer to “TROUBLESHOOTING” under “ELECTRIC STARTINGSYSTEM” on page 8-5.Starter motor operates, but theengine does not crank.Starter clutch malfunction Replace the starter clutch.Improper oil grade (starter clutchslipping)Change to recommended engineoil.Stuck piston or seized crankshaft Disassemble and check theengine. Replace defective parts.Symptom Possible cause ActionsSpark plug does not produce asparkRefer to “TROUBLESHOOTING” under “IGNITION SYSTEM” on page8-1.Fuel not supplied— Measure the fuel pressure.Empty fuel tank Fill the fuel tank with fuel.Clogged fuel tank cap breatherhole Clean the fuel tank cap.Clogged or damaged fuel hose Clean, repair, or replace the fuelhose.Fuel leakage Check the fuel passage. Repair orreplace as necessary.Clogged fuel pump Clean or replace the fuel pump.Cracks or damage in fuel pump Replace the fuel pump.Fuel pump malfunctionRefer to “TROUBLESHOOTING”under “FUEL PUMP SYSTEM” onpage 8-37.Failed or clogged fuel injector Replace the fuel injector.ECU failure Replace the ECU.