Yamaha F50HET Troubleshooting
| Engine Model: Yamaha F50HET |
| Engine Type: 4-stroke inline 4-cylinder SOHC 8-valve gasoline outboard engine |
| Total Displacement: 60.8 cu.in (996 cc) |
| Rated Engine Power: 50 Hp (36.8 kW) at 5500 rpm |
| Fuel System: Electronic Fuel Injection (EFI) |
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| Engine doesn't start or starts hard |
No fuel in fuel tank - Add fuel.
Low-quality gasoline - Use correct fuel grade.
Dirty fuel system - Check and clean.
Loose or disconnected spark plug wire - Check spark plug wiring connection, repair or change.
Defective spark plug - Install new spark plug.
Clogged fuel filter - Replace fuel filter.
Worn or damaged vapor separator needle valve - Change vapor separator needle valve.
Clogged fuel lines - Fuel lines need to be cleaned.
Fuel tank air vent closed or restricted - Open or clean air vent.
Fuel feed pump is faulty - Change or rebuild fuel feed pump.
Incorrectly adjusted or damaged throttle cable - Adjust properly or change the cable.
Valve clearance is incorrect - Need to adjust valve clearance.
Incorrect valve timing - Set the valve timing properly.
Low fuel pressure - Check system for fuel leaks or check low pressure fuel pump.
Clogged or worn fuel injector - Replace or clean if necessary.
Fuel regulator is not operating - Change fuel regulator.
ECM is not functioning - Replace ECM.
| Engine starts but then stops |
Spark plug is faulty - Change spark plug as required.
Worn or damaged vapor separator needle valve - Change vapor separator needle valve.
Defective ignition coil - Replace ignition coil as necessary.
Closed or restricted fuel tank air vent - Open or service air vent.
Fuel pump is faulty - Install new fuel pump or rebuild it.
Choke system malfunction - Inspect and replace choke system components.
Excessive valve clearance - Adjust valve clearance according to specifications.
Wrong valve timing - Adjust valve timing as required.
Broken or bad valve springs - Replace valve springs.
Stuck valves - Valves must be cleaned.
Low cylinder compression - Inspect and replace defective parts.
Fuel filter is plugged - Fuel filter needs to be replaced.
Dirty or faulty fuel injector - Clean or install new injector.
Engine oil level low - Add oil to the engine crankcase.
Faulty oil pump - Change oil pump as required.
Water intake screen is dirty - Clean and wash as required.
Thermostat is faulty - Change thermostat.
Water pump failure - Change water pump.
Ignition system failure - Inspect ignition system and change failed components.
Dirty or faulty fuel pump - Service or replace fuel pump.
Vapor separator needle valve is bend or wear - Change vapor separator needle valve.
Clogged fuel lines - Fuel lines must be clean.
Fuel tank air vent restricted or closed - Open or clean air vent.
Fuel filter is plugged - Change fuel filter.
Intake manifold air leaks - Change intake manifold gasket.
Water intake screen is dirty - Need to clean or wash.
Throttle valve and throttle link are defective or worn - Change faulty parts.
Fuel injector is damaged or dirty - Replace or clean if necessary.
Engine is under excessive load - Reduce the load.
Fuel pump or fuel injector is dirty - Replace or clean as required.
Ignition timing is improper - Ignition timing needs to be set properly.
Damaged thermostat - Change thermostat as required.
Water pump malfunction - Water pump need to be replaced.
Improper propeller diameter or pitch - Check the propeller size.
Propeller bent or damaged - Have propeller repaired or replaced.
Outboard engine is mounted too high or too low - Mount the motor as required.
Low engine oil level - Fill the crankcase with engine oil.
Defective oil pump - Change oil pump as required.
Water intake screen is dirty - Clean and wash as required.
Valve setting is incorrect - Set the valves correctly.
Stale gasoline - Change gasoline.
Engine is running overloaded - Load reducing required.
Low idle speed adjustment is incorrect - Correct idle settings.
Dirty or faulty fuel pump - Clean or replace fuel pump.
Crankshaft or main bearings wear - Crankshaft or bearings need to be replaced.
Piston rings or cylinder bore are damaged - Change defective components.
Fuel lines are clogged - Fuel lines need to be cleaned.
Fuel injector failure - Replace fuel injector.
Fuel pump is faulty or clogged - Clean or change fuel pump.
Ignition failure - Check ignition and replace faulty components.
Blown cylinder head gasket - Replace the gasket as required.
Powerhead components are worn - Replace defective components as required.
Stuck or burned valves - Service or change valves.
Improper propeller diameter or pitch - Replace propeller.
Propeller bent or damaged - Replace propeller.
Engine mounted at wrong transom height - Check the outboard engine mounting height.
Improper trim angle - Adjust trim angle correctly.
| Excessive fuel consumption |
Dirty or faulty fuel injector - Clean or install new injector.
Loose or faulty spark plug - Spark plug need to be tightened or replaced.
Sleeve, rings, or piston are damaged - Replace defective components.
ECU failure - Replace ECU.
| Excessive motor vibration |
Damaged or bent propeller - Replace propeller.
Propeller shaft damaged - Have propeller shaft replaced.
Weeds clogs the propeller - Remove and clean propeller.
Engine mounting bolt is not tightened - Tighten the bolt as required.
Damaged or loose steering pivot Tighten correctly or replace.
Battery capacity is low - Charge the battery.
Battery won’t hold charge - Battery needs to be serviced or replaced.
Bad battery terminals or disconnected wiring - Check cable connections and replace or service terminals.
Damaged starter motor - Repair or replace starter.
| Trim motor is running but trim system cannot move up or down |
Lack of oil - Check oil level and add oil as required.
Pump assembly is faulty - Check pump and change if required.
Leakage of manual drain valve - Close the valve or change it.
Pump driveshaft or motor damaged - Replace worn component.
| Trim does not fully up or down |
Pump assembly is defective - Change pump as required.
Tilt ram piston ball is not positioned correctly - Service or repair.
Damaged tilt ram piston O-ring - Install new O-ring.
Oil insufficient - Checking oil level and add if necessary.
Lower check valve not seating in port side trim ram - Secure valve properly.
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