Tohatsu M8B Troubleshooting
| Engine Model: Tohatsu M8B |
| Engine Type: 2-stroke 2-cylinder gasoline outboard engine |
| Total Displacement: 10.3 cu.in (169 cc) |
| Rated Engine Power: 8 Hp (5.9 kW) at 5500 rpm |
| Fuel System: Carburetor |
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| Engine difficult to start or will not start |
No fuel in fuel tank - Fill fuel up.
Low-quality gasoline - Change fuel.
Fuel system clogged - Repair or replace.
Defective spark plug wire connection - Check spark plug wiring connection, repair or change.
Damaged spark plug - Change spark plug.
Fuel filter is plugged - Replace or clean fuel filter.
Carburetor is not adjusted - Check carburetor float adjustment.
Fuel lines are dirty - Clean fuel lines.
Closed or clogged fuel tank air vent - Open or service air vent.
Fuel pump pressure is low - Install new fuel pump or rebuild it.
Worn or defective reed valve - Replace reed valve.
| Engine starts but stalls suddenly |
Spark plug is defective - Change spark plug.
Carburetor is faulty or dirty - Service or change carburetor.
Damaged ignition coil - Install a new ignition coil.
Fuel tank air vent clogged or closed - Fuel tank air vent need to be opened or cleaned.
Fuel pump pressure is low - Change or rebuild fuel pump.
Defective ignition - Check ignition system and replace faulty parts.
Fuel pump is damaged or dirty - Test fuel pump and change if necessary.
Carburetor is not adjusted - Check carburetor float adjustment.
Restricted fuel lines - Service fuel lines.
Fuel tank air vent restricted or closed - Fuel tank air vent need to be opened or cleaned.
Dirty fuel filter - Fuel filter needs changing.
Gaskets are damaged - Install new gaskets.
Engine overloaded - Reduce the load.
Too lean carburetor mixture - Adjust carburetor correctly.
Bad ignition timing - Ignition timing needs to be adjusted correctly.
Thermostat is defective - Replace thermostat.
Water pump failure - Change water pump.
Propeller selection improperly - Install correct propeller.
Damaged or improper size of propeller - Replace propeller.
Outboard engine is positioned too low or too high - Mount the motor as required.
Stale fuel - Change fuel.
Engine is under excessive load - Reduce the load.
Low idle speed set incorrectly - Adjust idle speed.
Fuel pump is damaged or dirty - Service or replace fuel pump.
Main bearings or crankshaft are worn out - Change or repair worn components.
Worn piston rings or cylinder bore - Change defective components.
Dirty or improperly adjusted carburetor - Service or properly adjust carburetor.
Dirty or faulty fuel pump - Inspect fuel pump and change as required.
Ignition system failure - Check ignition system and replace faulty parts.
Gaskets are damaged - Install new gaskets.
Powerhead parts are worn out - Defective parts need to be replaced.
Improper propeller diameter or pitch - Check the propeller size.
Damaged or improper size of propeller - Have propeller repaired or replaced.
Outboard motor mounting height is set incorrectly - Check the outboard engine mounting height.
Trim angle is incorrect - Adjust trim angle correctly.
| Engine using too much gasoline |
Incorrect adjustment of carburetor main jet - Adjust it properly.
Defective or loose spark plug - Re-tighten or replace spark plug.
Piston, sleeve, or rings are damaged - Replace defective parts as required.
| Motor vibrates excessively |
Damaged or bent propeller - Replace propeller.
Propeller shaft damaged - Replace propeller shaft.
Weeds clogs the propeller - Clean the propeller.
Motor mounting bolt is loose - Tighten the bolt as required.
Steering pivot is faulty or loose Tighten correctly or replace.
Low battery output voltage - Battery is drained, recharge it.
Battery will not hold charge - Service battery or change it.
Disconnected cables or faulty battery terminals - Check wire connections and change or service terminals.
Starter motor failure - Repair or replace starter.
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| Outboard Engines Technical Specifications |
| Small Engines Technical Specifications |
| Car Engines Technical Specifications |
| Industrial Engines Technical Specifications |
