Tohatsu M5B Troubleshooting
| Engine Model: Tohatsu M5B |
| Engine Type: 2-stroke 1-cylinder gasoline outboard engine |
| Total Displacement: 6.2 cu.in (102 cc) |
| Rated Engine Power: 5 Hp (3.7 kW) at 5500 rpm |
| Fuel System: Carburetor |
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| Engine hard to start or won't start |
Gas tank is empty - Add fuel.
Incorrect fuel grade - Use correct gasoline grade.
Air in fuel system - Bleed fuel system.
Disconnected or loose spark plug wire - Inspect spark plug wiring connection, change or repair.
Spark plug is damaged - Spark plug need to be replaced.
Fuel filter is dirty - Install new filter.
Carburetor is dirty - Wash, clean and adjust.
Fuel lines are clogged - Fuel lines must be clean.
Fuel tank air vent closed or restricted - Open or service air vent.
Low fuel pump pressure - Repair or change fuel pump.
Reed valve is worn or damaged - Replace reed valve.
| Engine starts and stalls suddenly |
Spark plug is defective - Replace spark plug.
Clogged or faulty carburetor - Clean or install new carburetor.
Defective ignition coil - Replace ignition coil as necessary.
Closed or clogged fuel tank air vent - Fuel tank air vent need to be opened or cleaned.
Lack of fuel pump pressure - Change or rebuild fuel pump.
Ignition system failure - Inspect ignition system and change failed components.
Dirty or faulty fuel pump - Service or replace fuel pump.
Problems with carburetor adjustment - Adjust as required.
Clogged fuel lines - Clean fuel lines.
Fuel tank air vent clogged or closed - Fuel tank air vent need to be opened or cleaned.
Fuel filter is dirty - Replace fuel filter.
Gaskets are defective - Install new gaskets.
Engine overloaded - Reduce engine load.
Carburetor mixture is too lean - Set the carburetor correctly.
Bad ignition timing - Adjust ignition timing as required.
Damaged thermostat - Install new thermostat.
Defective water pump - Change water pump as required.
Improper propeller diameter or pitch - Replace propeller.
Damaged or improper size of propeller - Replace propeller.
Outboard motor is positioned too low or too high - Position the engine correctly.
Stale fuel - Change gasoline.
Excessive engine load - Reduce engine load.
Wrong adjustment of low idle speed - Correct the settings.
Dirty or faulty fuel pump - Service or change fuel pump.
Crankshaft or main bearings failure - Change or repair worn components.
Damaged piston rings or cylinder bore - Replace faulty parts.
Clogged or improperly adjusted carburetor - Clean or properly adjust carburetor.
Dirty or damaged fuel pump - Test fuel pump and replace if necessary.
Ignition system failure - Inspect ignition system and change failed components.
Damaged gaskets - Change gaskets.
Damaged powerhead components - Replace defective components.
Incorrect propeller selection - Replace propeller.
Damaged or improper size of propeller - Have propeller repaired or replaced.
Engine mounted at wrong transom height - Check the outboard motor mounting height.
Improper trim angle - Adjust trim angle.
Incorrect carburetor main jet adjustment - Adjust main jet as required.
Loose or defective spark plug - Re-tighten or change the spark plug.
Worn sleeve, rings, or piston - Change faulty parts.
| Excessive motor vibration |
Damaged or improper size of propeller - Have propeller repaired or replaced.
Propeller shaft malfunction - Replace propeller shaft.
Weeds clogs the propeller - Clean the propeller.
Motor mounting bolt is loose - Tighten bolt.
Damaged or loose steering pivot Tighten or replace.
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| Outboard Engines Technical Specifications |
| Small Engines Technical Specifications |
| Car Engines Technical Specifications |
| Industrial Engines Technical Specifications |
