TOHATSU MFS 9.9D Owner's Manual page 79

80
TROUBLESHOOTING
Possible cause
Low compression
Carbon deposits in the combustion chamber
Incorrect valve clearance
Low oil pressure/level
Incorrect adjustment of throttle link
Insufficient cooling water flow, clogged or defective pump
Faulty thermostat
Cavitation or ventilation
Incorrect propeller selection
Damaged or bent propeller
Improper thrust rod position
Unbalanced load on boat
Transom too high or too low
A great deal of air is contained inside pump
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