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Tohatsu M2.5A2 Troubleshooting
The Tohatsu M2.5A2 is a 2-stroke 1-cylinder forced water-cooled gasoline outboard engine with a rated power of 2.5 hp (1.8 kW) at 3800-5200 rpm. The engine cylinder bore is 1.85" (47 mm) and piston stroke is 1.69" (43 mm). A 4.6 cubic inches (74.5 cc) outboard motor has a carburetor fuel system, starting system with manual starter, flywheel magneto capacitor discharge ignition system, manual tilt and handle tiller steering. The fuel tank capacity is 0.35 gal (1.4 liters). The propeller is made of aluminum and it has three blades.
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| Engine doesn't start or hard to start |
No fuel in fuel tank - Fill gasoline up.
Wrong fuel grade - Change gasoline.
Air in the fuel lines - Bleed the fuel lines.
Defective wiring connection of spark plug - Check spark plug wiring connection, repair or change.
Spark plug is defective - Spark plug need to be replaced.
Clogged fuel filter - Replace or clean fuel filter.
Carburetor is dirty - Wash, clean and adjust.
Clogged fuel lines - Service fuel lines.
Closed or restricted fuel tank air vent - Fuel tank air vent need to be opened or cleaned.
Low fuel pump pressure - Install new fuel pump or rebuild it.
Reed valve is faulty or worn - Replace reed valve.
| Engine starts but then stalls |
Spark plug is damaged - Install new spark plug.
Faulty or dirty carburetor - Clean or replace carburetor.
Defective ignition coil - Ignition coil must be replaced.
Closed or restricted fuel tank air vent - Fuel tank air vent need to be opened or cleaned.
Low fuel pump pressure - Replace or rebuild fuel pump.
| Irregular engine running |
Ignition system failure - Check ignition and replace faulty components.
Clogged or defective fuel pump - Clean or install new fuel pump.
Wrong carburetor adjustment - Adjusting carburetor correctly.
Fuel lines are dirty - Clean fuel lines.
Closed or clogged fuel tank air vent - Fuel tank air vent need to be opened or cleaned.
Fuel filter is clogged - Install new filter.
Worn gaskets - Change gaskets.
| Engine is overheated |
Engine is running overloaded - Reduce load.
Carburetor is running lean - Make the correct settings.
Ignition timing is improper - Ignition timing needs to be adjusted correctly.
Damaged thermostat - Change thermostat as required.
Water pump malfunction - Change water pump as required.
Propeller selection improperly - Replace propeller.
Damaged or improper size of propeller - Replace propeller.
Outboard engine is mounted too high or too low - Mount the motor as required.
| Engine noise or knocking |
Stale gasoline - Change fuel.
Engine is overloaded - Load reducing is recommended.
Incorrect low idle setting - Adjust the low idle speed.
Fuel pump is defective or dirty - Clean or install new fuel pump.
Worn crankshaft or main bearings - Repair or replace defective parts.
Cylinder bore or piston rings are damaged - Replace faulty parts.
| Low engine power |
Improperly adjusted or dirty carburetor - Adjust the carburetor properly or clean it.
Fuel pump is dirty or defective - Clean or replace fuel pump.
Ignition failure - Check ignition system and replace faulty parts.
Worn gaskets - Replace gaskets.
Powerhead components are damaged - Defective parts need to be replaced.
Propeller pitch or diameter incorrect - Install correct propeller.
Damaged or improper size of propeller - Replace propeller.
Engine mounted at wrong transom height - Check the outboard engine mounting height.
Incorrect trim angle - Adjust trim angle correctly.
| Engine using too much gasoline |
Improper adjustment of carburetor main jet - Adjust the carburetor main jet properly.
Spark plug is loose or faulty - Spark plug need to be tightened or replaced.
Piston, sleeve, or rings are damaged - Replace defective parts as required.
| Excessive motor vibration |
Damaged or bent propeller - Replace propeller.
Propeller shaft malfunction - Propeller shaft needs to be replaced.
Weeds wraped around propeller - Clean the propeller.
Engine mounting bolt is not tightened - Tighten bolt.
Damaged or loose steering pivot Tighten or replace.
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