Yamaha 15FMH Troubleshooting
| Engine Model: Yamaha 15FMH |
| Engine Type: 2-stroke 2-cylinder gasoline outboard engine |
| Total Displacement: 15 cu.in (246 cc) |
| Rated Engine Power: 15 Hp (11 kW) at 5500 rpm |
| Fuel System: Carburetor |
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| Engine starts up hard or doesn't start |
Empty gas tank - Fill it up.
Incorrect fuel grade - Change gasoline.
Air in the fuel system - Air bleeding.
Defective spark plug wire connection - Check the spark plug wire connection, repair or replace.
Spark plug is defective - Change spark plug as required.
Plugged fuel filter - Install new filter.
Carburetor is clogged - Clean the carburetor.
Dirty fuel lines - Clean fuel system lines.
Fuel tank air vent clogged or closed - Open or clean air vent.
Lack of fuel pump pressure - Install new fuel pump or rebuild it.
Reed valve is defective or worn - Replace reed valve as required.
| Engine starts and stops immediately |
Spark plug is defective - Spark plug need to be replaced.
Carburetor is dirty or defective - Carburetor needs to be replaced or cleaned.
Damaged ignition coil - Install a new ignition coil.
Fuel tank air vent restricted or closed - Open or clean air vent.
Lack of fuel pump pressure - Install new fuel pump or rebuild it.
Ignition system problems - Check ignition system and replace faulty parts.
Fuel pump is faulty or clogged - Clean or change fuel pump.
Carburetor problems - Carburetor diagnostics required.
Fuel lines clogging - Service fuel lines.
Fuel tank air vent clogged or closed - Open or service air vent.
Dirty fuel filter - Replace or clean fuel filter.
Gaskets are worn - Replace gaskets.
Engine is overloaded - Load reducing is recommended.
Too lean fuel mixture in carburetor - Set the carburetor properly.
Wrong ignition timing - Adjust ignition timing as required.
Thermostat is defective - Install new thermostat.
Water pump failure - Install new water pump.
Improper propeller diameter or pitch - Replace propeller.
Propeller bent or damaged - Have propeller repaired or replaced.
Outboard motor is mounted too high or too low - Position the engine correctly.
Low octane gasoline - Change fuel.
Engine is overloaded - Load reducing required.
Low idle speed adjustment is incorrect - Adjust as required.
Fuel pump is faulty or clogged - Clean or change fuel pump.
Crankshaft or main bearings are worn out - Replace crankshaft or bearings.
Piston rings or cylinder bore are worn - Replace defective parts.
Improperly or clogged carburetor - Service or properly adjust carburetor.
Fuel pump is faulty or clogged - Clean or change fuel pump.
Ignition system failure - Inspect ignition system and change failed components.
Gaskets are worn - Install new gaskets.
Powerhead components are worn - Replace defective components.
Propeller pitch or diameter incorrect - Install correct propeller.
Damaged or improper size of propeller - Replace propeller.
Outboard motor mounting height is set incorrectly - Check the outboard engine mounting height.
Incorrect trim angle - Adjust trim angle.
| Engine using too much gasoline |
Carburetor main jet is incorrectly adjusted - Adjust it correctly.
Spark plug is loose or faulty - Tighten or change the spark plug.
Piston, sleeve, or rings are damaged - Change defective parts.
| Engine vibrates excessively |
Damaged or improper size of propeller - Replace propeller.
Propeller shaft damaged - Propeller shaft needs to be replaced.
Weeds in the propeller - Remove and clean propeller.
Motor mounting bolt is loose - Tighten bolt.
Steering pivot is faulty or loose Tighten correctly or replace.
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| Outboard Engines Technical Specifications |
| Small Engines Technical Specifications |
| Car Engines Technical Specifications |
| Industrial Engines Technical Specifications |
