Tohatsu MFS20E Troubleshooting
| Engine Model: Tohatsu MFS20E |
| Engine Type: 4-stroke 2-cylinder SOHC gasoline outboard engine |
| Total Displacement: 20.3 cu.in (333 cc) |
| Rated Engine Power: 20 Hp (14.7 kW) at 6000 rpm |
| Fuel System: Fuel Injection |
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| Engine starts up hard or will not start |
Empty gas tank - Fill it up.
Improper fuel grade - Change gasoline.
Dirt and debris in fuel system - Remove debris and dirt.
Damaged spark plug wiring connection - Inspect spark plug wiring connection, change or repair.
Spark plug is faulty - Change spark plug.
Fuel filter is clogged - Change fuel filter.
Vapor separator needle valve is bend or wear - Replace needle valve.
Clogged fuel lines - Clean fuel lines.
Closed or restricted fuel tank air vent - Open or clean air vent.
Faulty fuel feed pump - Replace or repair fuel pump.
Throttle cable is adjusted incorrectly or damaged - Change cable or adjust correctly.
Valve clearance is improper - Adjust valve clearance.
Valve timing is wrong - Set the valve timing correctly.
Low fuel pressure - Check low pressure fuel pump or check system for fuel leaks.
Dirty or faulty fuel injector - Replace or clean if necessary.
Fuel regulator malfunction - Replace fuel regulator.
Electronic control modul failure - Install new ECM.
| Engine starts and immediately shuts off |
Damaged spark plug - Change spark plug.
Worn or defective vapor separator needle valve - Change vapor separator needle valve.
Faulty ignition coil - Ignition coil must be replaced.
Fuel tank air vent closed or restricted - Fuel tank air vent need to be opened or cleaned.
Fuel pump is faulty - Replace or repair fuel pump.
Faulty choke system - Check and repair choke system.
Excessive valve clearance - Adjust valve clearance.
Incorrect valve timing - Set the valve timing properly.
Valve springs are loose or broken - Install new valve springs.
Stuck valves - Service the valves.
Bad cylinder compression - Check and change damaged parts.
Fuel filter is plugged - Fuel filter needs changing.
Dirty or faulty fuel injector - Clean or install new injector.
Engine oil level low - Need to add engine oil.
Damaged oil pump - Install new oil pump.
Clogged water intake - Clean and wash as required.
Thermostat is defective - Install new thermostat.
Water pump failure - Install new water pump.
Defective ignition system - Check ignition and replace faulty components.
Fuel pump is faulty or clogged - Service or change fuel pump.
Vapor separator needle valve is damaged or worn - Install new needle valve.
Dirty fuel lines - Clean fuel system lines.
Fuel tank air vent closed or restricted - Fuel tank air vent need to be opened or cleaned.
Fuel filter is plugged - Replace or clean fuel filter.
Intake manifold is air leaking - Replace intake manifold gasket.
Clogged water intake - Need to wash or clean.
Throttle link and throttle valve are wear or damaged - Change faulty parts.
Dirty or faulty fuel injector - Replace or clean if necessary.
Engine is running overloaded - Reduce engine load.
Clogged fuel pump or fuel injector - Clean or replace if necessary.
Improper ignition timing - Set the ignition timing correctly.
Thermostat is defective - Change thermostat.
Defective water pump - Change water pump as required.
Improper propeller diameter or pitch - Check the propeller size.
Damaged or bent propeller - Replace propeller.
Outboard engine is positioned too low or too high - Mount the motor as required.
Engine oil level is insufficient - Check and refill engine oil.
Faulty oil pump - Install new oil pump.
Clogged water intake - Clean and wash as required.
Valve setting is improper - Adjust valves correctly.
Stale or low octane fuel - Change fuel.
Excessive engine load - Reduce the load.
Improperly adjusted low idle speed - Correct idle adjustment.
Clogged or defective fuel pump - Test fuel pump and change if necessary.
Worn main bearings or crankshaft - Change defective components as required.
Worn piston rings or cylinder bore - Replace defective components.
Fuel lines clogging - Fuel lines must be clean.
Fuel injector is fault - Inspect fuel injector and change as required.
Fuel pump is faulty or clogged - Clean or install new fuel pump.
Ignition system is defective - Check ignition system and replace faulty parts.
Cylinder head gasket is blown - Replace the gasket as required.
Faulty powerhead parts - Replace defective parts.
Stuck or burned valves - Clean or replace valves.
Incorrect propeller selection - Check the propeller size.
Damaged or bent propeller - Replace propeller.
Outboard engine mounting height improperly - Check the outboard motor mounting height.
Incorrect trim angle - Adjust trim angle correctly.
Damaged or clogged fuel injector - Clean or install new injector.
Defective or loose spark plug - Change or re-tighten spark plug.
Worn sleeve, rings, or piston - Replace defective components as required.
ECU failure - Replace ECU.
Damaged or improper size of propeller - Replace propeller.
Propeller shaft malfunction - Propeller shaft needs to be replaced.
Weeds clogs the propeller - Remove weeds from propeller.
Motor mounting bolt is loose - Tighten bolt.
Steering pivot is faulty or loose Tighten correctly or replace.
Low battery power - Battery needs to be recharged.
Battery drains quickly - Service charging system or install new battery.
Disconnected battery cables or bad terminals - Check battery wires and service or replace terminals.
Starter motor is defective - Starter should be changed.
| Trim motor runs but trim system does not move up or down |
Insufficient oil - Need to add the oil.
Defective pump assembly - Inspect pump and change as required.
Manual shut-off valve leaks - Valve need to be closed or changed.
Motor or pump driveshaft faulty - Replace defective component.
| Trim cannot be fully up or down |
Defective pump assembly - Replace pump.
Tilt ram piston ball is not positioned correctly - Service or repair.
Tilt ram piston O-ring damaged - Change O-ring.
Oil level is insufficient - Fill up oil to required level.
Lower check valve not seating in port side trim ram - Secure valve properly.
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