Yanmar BY series, Service Manual

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TROUBLESHOOTING
BY Service Manual 13-7
Troubleshooting Chart
Vibration - Drive Disengaged
Vibration - Drive Engaged
Black Smoke Under Load
Clogged air filter Replace / clean air filter
Incorrect valve timing Check / correct camshaft installation
Defective (leaking) fuel injector Test / replace fuel injector
Low charge air pressure
Clean or replace air filter
Damaged turbocharger
Excessive exhaust backpressure Correct as necessary
Plugged intake port(s) Repair as necessary
Problem / Symptom Cause Action
Problem / Symptom Cause Action
Rough at All Engine Speeds
Air in fuel system Bleed fuel system
Faulty fuel injector Replace as necessary
Leaking cylinder head gasket Replace
Damaged intake or exhaust valves Repair as necessary
Incorrect injection pressure
Check / replace fuel pressure regulator
Check / replace high-pressure fuel pump
Vibration Increases with Engine Speed
(Stern Drive Models)
Worn or damaged universal joints Replace universal joints
Problem / Symptom Cause Action
Rough at All Speeds
Engine and propeller shaft misaligned Check and adjust
Leaking cylinder head gasket Replace
Bent propeller shaft Replace as necessary
Rough at Higher Speeds
Bent propeller Replace as necessary
Slipping clutch / clutch dog Repair as necessary
Incorrect injection pressure
Check / replace fuel pressure regulator
Check / replace high-pressure fuel pump