Vibration - Drive Disengaged; Vibration - Drive Engaged - Yanmar BY Series Service Manual

Troubleshooting Chart
Problem / Symptom
Black Smoke Under Load

Vibration - Drive Disengaged

Problem / Symptom
Rough at All Engine Speeds
Vibration Increases with Engine Speed
(Stern Drive Models)

Vibration - Drive Engaged

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