Yamaha 25MSH Troubleshooting
| Engine Model: Yamaha 25MSH |
| Engine Type: 2-stroke 2-cylinder short shaft gasoline outboard engine |
| Total Displacement: 24.1 cu.in (395 cc) |
| Rated Engine Power: 25 Hp (18.4 kW) at 6000 rpm |
| Fuel System: Carburetor |
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| Engine will not start or hard to start |
No gasoline in tank - Add gasoline.
Low-quality gasoline - Use quality fuel.
There is air in the fuel system - Bleed the system.
Spark plug wire is loose or disconnected - Inspect the spark plug wire connection, replace or repair.
Defective spark plug - Spark plug need to be replaced.
Dirty fuel filter - Install new filter.
Carburetor is not adjusted - Check carburetor float adjustment.
Dirt in the fuel lines - Fuel lines need to be cleaned.
Closed or clogged fuel tank air vent - 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 - Install new reed valve.
| Engine stalls after starting |
Spark plug is faulty - Replace spark plug.
Carburetor is clogged or faulty - Replace or service carburetor.
Defective ignition coil - Install a new ignition coil.
Closed or clogged fuel tank air vent - Fuel tank air vent need to be opened or cleaned.
Fuel pump pressure is low - Install new pump or repair it.
Ignition failure - Check ignition system and replace faulty parts.
Clogged or damaged fuel pump - Service or replace fuel pump.
Carburetor is not adjusted - Check carburetor float adjustment.
Dirt in the fuel lines - Fuel lines need to be cleaned.
Closed or restricted fuel tank air vent - Fuel tank air vent need to be opened or cleaned.
Dirty fuel filter - Change fuel filter.
Gaskets are damaged - Replace gaskets.
Excessive engine load - Load reducing is recommended.
Carburetor is running lean - Use proper settings.
Ignition timing is wrong - Adjust ignition timing as required.
Thermostat is faulty - Change thermostat as required.
Water pump malfunction - Install new water pump.
Incorrect propeller selection - Check the propeller size.
Damaged or bent propeller - Replace propeller.
Outboard motor is mounted too high or too low - Position the engine correctly.
Stale fuel - Use correct fuel.
Engine is overloaded - Load reducing required.
Low idle speed setting is incorrect - Correct idle adjustment.
Fuel pump is faulty or clogged - Service or replace fuel pump.
Main bearings or crankshaft are worn out - Replace crankshaft or bearings.
Worn piston rings or cylinder bore - Replace defective parts.
Clogged or improperly adjusted carburetor - Carburetor needs to be adjusted correctly or cleaned.
Clogged or damaged fuel pump - Check fuel pump and change if required.
Defective ignition - Inspect ignition system and change failed components.
Damaged gaskets - Install new gaskets.
Powerhead parts are damaged - Change defective parts.
Propeller selection improperly - Replace propeller.
Propeller bent or damaged - Replace propeller.
Engine mounted at wrong transom height - Adjust the engine to correct transom height.
Improper trim angle - Adjust trim angle correctly.
| Excessive fuel consumption |
Incorrect carburetor main jet adjustment - Adjust it correctly.
Loose or faulty spark plug - Spark plug need to be tightened or replaced.
Worn sleeve, piston, or rings - Replace defective components as required.
| Motor vibrates excessively |
Damaged or improper size of propeller - Have propeller repaired or replaced.
Damaged propeller shaft - Replace propeller shaft.
Weeds clogs the propeller - Remove weeds from propeller.
Engine mounting bolt is not tightened - Tighten the bolt as required.
Steering pivot is faulty or loose Tighten or replace.
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| Outboard Engines Technical Specifications |
| Small Engines Technical Specifications |
| Car Engines Technical Specifications |
| Industrial Engines Technical Specifications |
