
TROUBLESHOOTING
Troubleshooting Chart
12/05
BY Service Manual
13-7
© 2009 Yanmar Marine International
Vibration - Drive Disengaged
Vibration - Drive Engaged
Black Smoke Under Load
Clogged air filter
Replace air filter
Incorrect valve timing
Check / correct camshaft installation
Defective (leaking) fuel injector
Test / replace fuel injector
Low charge air pressure
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