Tohatsu M70C Troubleshooting
| Engine Model: Tohatsu M70C |
| Engine Type: 2-stroke 3-cylinder gasoline outboard engine |
| Total Displacement: 57.2 cu.in (938 cc) |
| Rated Engine Power: 70 Hp (52 kW) at 5500 rpm |
| Fuel System: Carburetor |
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| Engine hard to start or won't start |
No fuel in fuel tank - Fill gasoline up.
Improper fuel grade - Use correct gasoline grade.
Clogged fuel system - Remove clogging.
Faulty spark plug wire connection - Check spark plug wiring connection, repair or change.
Faulty spark plug - Change spark plug.
Fuel filter is dirty - Replace fuel filter.
Carburetor incorrectly set - Set carb correctly.
Fuel lines are dirty - Clean fuel lines.
Fuel tank air vent restricted or closed - Fuel tank air vent need to be opened or cleaned.
Lack of fuel pump pressure - Replace or rebuild fuel pump.
Reed valve is worn or damaged - Replace reed valve as required.
| Engine starts but then shuts off |
Spark plug is defective - Change spark plug as required.
Clogged or defective carburetor - Clean or replace carburetor.
Ignition coil is defective - Replace ignition coil as necessary.
Fuel tank air vent restricted or closed - Fuel tank air vent need to be opened or cleaned.
Low fuel pump pressure - Change or rebuild fuel pump.
Ignition system malfunction - Inspect ignition system and change failed components.
Fuel pump is clogged or faulty - Test fuel pump and replace if necessary.
Carburetor is clogged - Clean the carburetor.
Dirty fuel lines - Clean fuel lines.
Fuel tank air vent restricted or closed - Open or service air vent.
Fuel filter is dirty - Change fuel filter.
Gaskets are defective - Change gaskets.
Engine is under excessive load - Load reducing is recommended.
Too lean fuel mixture in carburetor - Use proper settings.
Incorrect ignition timing - Adjust ignition timing as required.
Defective thermostat - Replace thermostat.
Water pump is defective - Change water pump as required.
Propeller selection improperly - Replace propeller.
Damaged or improper size of propeller - Replace propeller.
Outboard motor is positioned too low or too high - Position the engine correctly.
Stale or low octane fuel - Use correct fuel.
Engine overload - Reduce load.
Too low idle RPM - Test and adjust.
Dirty or defective fuel pump - Clean or install new fuel pump.
Main bearings or crankshaft wear - Replace crankshaft or bearings.
Piston rings or cylinder bore are worn - Replace defective parts.
Incorrectly adjusted or dirty carburetor - Clean or properly adjust carburetor.
Fuel pump is faulty or clogged - Service or replace fuel pump.
Defective ignition - Check ignition and replace faulty components.
Worn gaskets - Change gaskets.
Powerhead parts are damaged - Replace defective components.
Propeller selection improperly - Install correct propeller.
Damaged or improper size of propeller - Have propeller repaired or replaced.
Engine mounted at wrong transom height - Adjust the outboard motor height correctly.
Improper trim angle - Adjust trim angle.
| Excessive fuel consumption |
Incorrect adjustment of carburetor main jet - Adjust the carburetor main jet correctly.
Loose or faulty spark plug - Tighten or change the spark plug.
Worn sleeve, piston, or rings - Replace defective components as required.
| Engine vibrates excessively |
Damaged or bent propeller - Replace propeller.
Propeller shaft damaged - Replace propeller shaft.
Weeds wraped around propeller - Remove weeds from propeller.
Engine mounting bolt is not tightened - Tighten bolt.
Steering pivot is faulty or loose Tighten or replace.
Battery voltage is low - Battery is drained, charge it.
Battery discharges quickly - Service or replace the battery.
Battery cables are disconnected or terminals are faulty - Connect cables correctly or replace terminals.
Starter motor is faulty - Starter should be changed.
| Trim motor is running but trim system cannot move up or down |
Not enough oil - Fill up oil.
Defective pump assembly - Test pump and replace if necessary.
Leakage of manual drain valve - Close the valve or change it.
Faulty pump driveshaft or motor - Change worn component.
| Trim cannot be fully up or down |
Pump assembly faulty - Replace pump.
Tilt ram piston ball is displaced - Clean or repair.
Tilt ram piston O-ring is worn - Replace O-ring.
Oil insufficient - Check oil level and add oil as required.
Lower check valve not seating in port side trim ram - Install valve correctly.
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