Yamaha 9.9 FMH Troubleshooting
| Engine Model: Yamaha 9.9 FMH |
| Engine Type: 2-stroke 2-cylinder gasoline outboard engine |
| Total Displacement: 15 cu.in (246 cc) |
| Rated Engine Power: 9.9 Hp (7.3 kW) at 5500 rpm |
| Fuel System: Carburetor |
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| Engine starts up hard or will not start |
Gas tank is empty - Fill gasoline up.
Incorrect fuel grade - Use quality fuel.
Clogged fuel system - Remove clogging.
Spark plug wire is disconnected or loose - Inspect spark plug wiring connection, change or repair.
Spark plug is faulty - Change spark plug.
Plugged fuel filter - Change fuel filter.
Carburetor not adjusted - Adjust according to instructions.
Restricted fuel lines - Fuel lines must be clean.
Fuel tank air vent clogged or closed - Open or clean air vent.
Lack of fuel pump pressure - Replace or repair fuel pump.
Reed valve is worn or damaged - Install new reed valve.
| Engine starts but immediately shuts off |
Spark plug is faulty - Change spark plug as required.
Defective or clogged carburetor - Repair or clean carburetor.
Defective ignition coil - Ignition coil must be replaced.
Closed or clogged fuel tank air vent - Open or service air vent.
Low fuel pump pressure - Install new fuel pump or rebuild it.
Ignition system problems - Inspect ignition system and change failed components.
Fuel pump is defective or dirty - Check fuel pump and replace if necessary.
Carburetor settings incorrect - Adjusting as required.
Restricted fuel lines - Service fuel lines.
Closed or clogged fuel tank air vent - Open or service air vent.
Fuel filter is clogged - Replace fuel filter.
Worn gaskets - Replace gaskets.
Excessive engine load - Reduce the load.
Carburetor is running lean - Set the carburetor correctly.
Ignition timing is improper - Set the ignition timing correctly.
Faulty thermostat - Install new thermostat.
Water pump malfunction - Water pump 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 engine is mounted too high or too low - Mount the motor as required.
| Abnormal engine knocking or noise |
Low octane gasoline - Use correct fuel.
Excessive engine load - Reduce the load.
Low idle speed setting is incorrect - Correct idle settings.
Fuel pump is clogged or faulty - Check fuel pump and replace if necessary.
Main bearings or crankshaft wear - Have bearings or crankshaft replaced.
Piston rings or cylinder bore are worn - Change defective components.
Carburetor is dirty or incorrectly adjusted - Adjust the carburetor correctly or clean it.
Clogged or damaged fuel pump - Check fuel pump and change if required.
Defective ignition - Inspect ignition system and change failed components.
Gaskets are damaged - Change gaskets.
Powerhead components are damaged - Replace defective components.
Improper propeller diameter or pitch - Replace propeller.
Damaged or improper size of propeller - Replace propeller.
Outboard engine mounting height improperly - Check the outboard motor mounting height.
Improper trim angle - Make the correct trim angle adjustment.
| Excessive fuel consumption |
Incorrect adjustment of carburetor main jet - Adjust the carburetor main jet properly.
Loose or faulty spark plug - Change or re-tighten spark plug.
Worn rings, piston, or sleeve - Replace faulty components.
| Motor vibrates excessively |
Damaged or improper size of propeller - Replace propeller.
Damaged propeller shaft - Replace propeller shaft.
Weeds wraped around propeller - Clean the propeller.
Motor mounting bolt is loose - Tighten bolt.
Loose or faulty steering pivot Tighten correctly or replace.
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| Outboard Engines Technical Specifications |
| Small Engines Technical Specifications |
| Car Engines Technical Specifications |
| Industrial Engines Technical Specifications |
