Yamaha 50HMHD Troubleshooting
| Engine Model: Yamaha 50HMHD |
| Engine Type: 2-stroke inline 3-cylinder gasoline outboard engine |
| Total Displacement: 42.6 cu.in (698 cc) |
| Rated Engine Power: 50 Hp (36.8 kW) at 5000 rpm |
| Fuel System: Carburetor |
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| Engine doesn't start or starts hard |
No gasoline in tank - Add gasoline.
Improper fuel grade - Use quality gasoline.
Air in the fuel lines - Bleed the fuel lines.
Faulty spark plug wire connection - Inspect spark plug wiring connection, change or repair.
Defective spark plug - Change spark plug.
Plugged fuel filter - Replace fuel filter.
Problems with carburetor adjustment - Adjust as required.
Dirt in the fuel lines - Fuel lines need to be cleaned.
Fuel tank air vent closed or restricted - Fuel tank air vent need to be opened or cleaned.
Lack of fuel pump pressure - Change or rebuild fuel pump.
Reed valve is defective or worn - Replace reed valve as required.
| Engine stops after starting |
Faulty spark plug - Spark plug need to be replaced.
Defective or clogged carburetor - Replace or service carburetor.
Faulty ignition coil - Install a new ignition coil.
Fuel tank air vent clogged or closed - Fuel tank air vent need to be opened or cleaned.
Lack of fuel pump pressure - Repair or change fuel pump.
Ignition system problems - Inspect ignition system and change faulty parts.
Fuel pump is defective or dirty - Clean or install new fuel pump.
Carburetor incorrectly set - Set carb correctly.
Restricted fuel lines - Fuel lines must be clean.
Fuel tank air vent clogged or closed - Fuel tank air vent need to be opened or cleaned.
Fuel filter is dirty - Replace fuel filter.
Worn gaskets - Install new gaskets.
Engine is under excessive load - Reduce the load.
Carburetor mixture is too lean - Adjust carburetor correctly.
Improper ignition timing - Adjust ignition timing as required.
Thermostat is faulty - Change thermostat as required.
Faulty water pump - Water pump need to be replaced.
Propeller pitch or diameter incorrect - Replace propeller.
Propeller bent or damaged - Have propeller repaired or replaced.
Outboard motor is positioned too low or too high - Position the engine correctly.
Low octane fuel - Use proper fuel.
Engine is under excessive load - Load reducing is recommended.
Low idle speed setting is incorrect - Adjust idle speed.
Fuel pump is defective or dirty - Clean or change fuel pump.
Main bearings or crankshaft wear - Repair or replace defective parts.
Piston rings or cylinder bore are damaged - Replace faulty parts.
Incorrectly adjusted or dirty carburetor - Adjust the carburetor correctly or clean it.
Fuel pump is clogged or faulty - Clean or install new fuel pump.
Ignition system malfunction - Inspect ignition system and change failed components.
Worn gaskets - Change gaskets.
Faulty powerhead components - Replace defective parts as required.
Propeller pitch or diameter incorrect - Replace propeller.
Propeller bent or damaged - Replace propeller.
Motor mounted at incorrect height on transom - Check the outboard motor mounting height.
Trim angle is incorrect - Adjust trim angle correctly.
Improper carburetor main jet adjustment - Adjust the carburetor main jet correctly.
Spark plug is defective or loose - Tighten or replace spark plug.
Rings, sleeve, or piston are damaged - Replace faulty components as required.
| Excessive motor vibration |
Damaged or bent propeller - Replace propeller.
Propeller shaft malfunction - Have propeller shaft replaced.
Weeds in the propeller - Clean the propeller.
Engine mounting bolt is not tightened - Tighten bolt.
Steering pivot is faulty or loose Tighten or replace.
Low battery capacity - Battery is drained, charge it.
Battery drains quickly - Service or replace the battery.
Terminals are faulty or battery cables are disconnected - Check wiring and clean or replace terminals.
Starter motor is damaged - Starter should be replaced.
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| Outboard Engines Technical Specifications |
| Small Engines Technical Specifications |
| Car Engines Technical Specifications |
| Industrial Engines Technical Specifications |
