Tohatsu MFS20C Troubleshooting
| Engine Model: Tohatsu MFS20C |
| Engine Type: 4-stroke 2-cylinder SOHC gasoline outboard engine |
| Total Displacement: 21.4 cu.in (351 cc) |
| Rated Engine Power: 20 Hp (14.7 kW) at 6000 rpm |
| Fuel System: Fuel Injection |
____________________________________________________________________________________
| Engine won't start or hard to start |
Fuel tank is empty - Add fuel.
Low-quality gasoline - Use quality gasoline.
Air in fuel tank - Bleed fuel tank.
Loose or disconnected spark plug wire - Inspect the spark plug wire connection, replace or repair.
Spark plug is faulty - Replace spark plug.
Plugged fuel filter - Change fuel filter.
Damaged or wear vapor separator needle valve - Replace needle valve.
Fuel lines are clogged - Service fuel lines.
Fuel tank air vent closed or restricted - Fuel tank air vent need to be opened or cleaned.
Fuel feed pump malfunction - Replace or rebuild fuel feed pump.
Unadjusted or worn throttle cable - Replace cable or adjust correctly.
Improper valve clearance - Check and adjust.
Valve timing is incorrect - Adjust valve timing correctly.
Low fuel pressure - Inspect fuel system for leaks or inspect low pressure fuel pump.
Fuel injector is faulty or clogged - Replace or clean as required.
Fuel regulator is not operating - Change fuel regulator.
ECM failure - Install new ECM.
| Engine starts and stalls suddenly |
Defective spark plug - Install new spark plug.
Worn or defective vapor separator needle valve - Replace needle valve.
Faulty ignition coil - Change ignition coil as required.
Fuel tank air vent closed or restricted - Fuel tank air vent need to be opened or cleaned.
Fuel pump defective - Install new fuel pump or rebuild it.
Choke system is damaged - Check and repair choke system.
Valve clearance is improper - Adjust valve clearance.
Valve timing is wrong - Set the valve timing properly.
Valve springs are worn or loose - Replace valve springs.
Valves are stuck - Clean the valves.
Low cylinder compression - Check and repair damaged parts.
Fuel filter is plugged - Install new filter.
Dirty or faulty fuel injector - Clean or replace as required.
Lack of engine oil - Fill the crankcase with engine oil.
Faulty oil pump - Install new oil pump.
Water intake is clogged - Wash or clean as required.
Faulty thermostat - Change thermostat.
Water pump malfunction - Change water pump.
Ignition system malfunction - Inspect ignition system and change failed components.
Dirty or faulty fuel pump - Service or replace fuel pump.
Vapor separator needle valve is worn or defective - Change vapor separator needle valve.
Fuel lines clogging - Clean fuel system lines.
Fuel tank air vent restricted or closed - Open or service air vent.
Plugged fuel filter - Install new filter.
Intake manifold air leaks - Install new gasket.
Water intake screen is dirty - Need to clean or wash.
Throttle valve and throttle link are damaged or worn - Replace faulty parts.
Fuel injector is clogged or malfunction - Replace or clean as required.
Engine overload - Reduce engine load.
Fuel injector or fuel pump is clogged - Replace or clean as required.
Ignition timing is incorrect - Ignition timing needs to be set properly.
Defective thermostat - Thermostat need to be replaced.
Faulty water pump - Change water pump as required.
Propeller pitch or diameter incorrect - Replace propeller.
Damaged or bent propeller - Have propeller repaired or replaced.
Outboard engine is mounted too high or too low - Mount the motor as required.
Insufficient engine oil - Add oil to the engine crankcase.
Damaged oil pump - Change oil pump.
Dirty water intake screen - Clean and wash as required.
Wrong valve setting - Valves needs to be adjusted properly.
Low octane fuel - Use proper fuel.
Engine is running overloaded - Reduce load.
Incorrectly adjusted low idle speed - Correct idle settings.
Dirty or damaged fuel pump - Check fuel pump and change if required.
Main bearings or crankshaft wear - Repair or replace defective parts.
Piston rings or cylinder bore are worn - Change faulty components.
Dirt in the fuel lines - Service fuel lines.
Fuel injector failure - Inspect fuel injector and change as required.
Dirty or damaged fuel pump - Clean or replace fuel pump.
Ignition system problems - Inspect ignition system and change failed components.
Cylinder head gasket is defective - Install new head gasket.
Faulty powerhead parts - Replace defective components as required.
Stuck or burned valves - Replace or clean valves.
Incorrect propeller selection - Check the propeller size.
Damaged or bent propeller - Replace propeller.
Motor mounted at incorrect height on transom - Have motor adjusted to proper transom height.
Improper trim angle - Adjust trim angle correctly.
| Engine using too much gasoline |
Dirty or faulty fuel injector - Clean or replace if necessary.
Loose or faulty spark plug - Re-tighten or replace spark plug.
Piston, sleeve, or rings are damaged - Change faulty parts.
ECU is not functioning - Change electronic control unit.
| Engine vibrates excessively |
Damaged or improper size of propeller - Replace propeller.
Propeller shaft damaged - Have propeller shaft replaced.
Weeds clogs the propeller - Remove weeds from propeller.
Engine mounting bolt is not tightened - Tighten bolt.
Damaged or loose steering pivot Tighten correctly or replace.
Low battery output - Charge the battery.
Battery drains quickly - Battery needs service or replacement.
Disconnected wiring or bad battery terminals - Connect wires properly or change terminals.
Starter motor is damaged - Repair or install a new starter.
| Trim motor is running but trim system cannot move up or down |
Low oil level - Fill up oil to required level.
Pump assembly is defective - Check pump and replace if necessary.
Manual release valve leaking - Close the valve fully or replace it.
Pump driveshaft or motor damaged - Replace defective component.
| Trim cannot be fully up or down |
Pump assembly faulty - Replace pump.
Tilt ram piston ball is displaced - Service or repair.
Tilt ram piston O-ring is worn - Install new O-ring.
Oil insufficient - Fill up oil.
Lower check valve is not properly secured in port side trim ram - Install valve correctly.
____________________________________________________________________________________
| Outboard Engines Technical Specifications |
| Small Engines Technical Specifications |
| Car Engines Technical Specifications |
| Industrial Engines Technical Specifications |
