Troubleshooting List - TOHATSU MFS 25D Service Manual

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Troubleshooting
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1. Troubleshooting List

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Fuel tank is empty
Connection of the fuel system is incomplete
Fuel system is taking in air or is clogged
Fuel pipe is twisted or damaged
Air vent screw of the fuel tank is not open
Fuel filter, fuel pump, vapor separator, or injector is clogged
Performance of the fuel pump or vapor separator has dropped
Gasoline is of poor quality
Fuel is not fed under pressure by the primer valve or primer valve is clogged
Engine oil is of poor quality
Excessive engine oil (is generating exhaust smoke)
* * Insufficient Engine oil (activated the oil pressure switch)
* * Defective Oil pump (activated the oil pressure switch)
* * Electrical parts are defective, wiring is disconnected, contact is poor, grounding is poor
Specified spark plug is not being used
Spark plug is dirty or worn
Ignition is poor (ignition system is defective)
Stop switch short-circuited
Stop switch is not locked or not fully inserted
Rectifier is defective
Battery life is up, charge is insufficient, electrolyte level is low,
battery terminal is loose or corroded
Fuse is blown
Shift lever is not in the neutral (N) position
Key switch or starter switch is defective
Starter motor or starter solenoid is defective
Power tilt switch or power tilt relay is defective
Power tilt fluid has air contamination
Compression pressure is insufficient
Valve timing is incorrect (belt is stretched, belt is installed incorrectly)
Valve clearance is insufficient
Intake or exhaust valve seat sealing is defective
Piston, piston ring, or cylinder is excessively worn
Carbon has built up in the combustion chamber
Spark plug is loose
* * Cooling water is insufficient, pump is defective, or is clogged
* * Thermostat operation is defective
* * Anti-ventilation plate is damaged
Mismatched propeller is being used
Propeller is damaged or deformed
Thrust rod position is incorrect
Load position is unbalanced
Transom is too high or too low
Throttle opening is insufficient
* Low speed ESG is activated
Probable Cause
4st 25/30 2022