Yamaha T50LB Troubleshooting
| Engine Model: Yamaha T50LB |
| 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) |
____________________________________________________________________________________
| Engine starts hard or doesn't start |
Empty fuel tank - Add fuel.
Improper fuel grade - Use correct gasoline grade.
Air or water in fuel system - Remove water or air from fuel system.
Spark plug wire is disconnected or loose - Inspect spark plug wiring connection, change or repair.
Defective spark plug - Replace spark plug.
Fuel filter is plugged - Replace or clean fuel filter.
Worn or damaged vapor separator needle valve - Replace needle valve.
Clogged fuel lines - Fuel lines must be clean.
Closed or clogged fuel tank air vent - Open or clean air vent.
Faulty fuel feed pump - Replace or repair fuel pump.
Worn or improperly adjusted choke cable - Adjust properly or change the cable.
Valve clearance is not correct - Adjust to proper valve clearance.
Wrong valve timing - Adjust valve timing correctly.
Low fuel pressure - Inspect low pressure fuel pump or inspect fuel system for leaks.
Clogged or worn fuel injector - Replace or clean as required.
Fuel regulator is defective - Replace fuel regulator.
Electronic control modul failure - Install new ECM.
| Engine starts and then shuts off |
Damaged spark plug - Change spark plug as required.
Vapor separator needle valve is damaged or worn - Replace needle valve.
Ignition coil is damaged - Ignition coil should be replaced.
Fuel tank air vent restricted or closed - Fuel tank air vent need to be opened or cleaned.
Fuel pump malfunction - Repair or change fuel pump.
Choke system is damaged - Check and repair choke system.
Valve clearance is not correct - Need to adjust valve clearance.
Valve timing is incorrect - Adjust valve timing as required.
Broken or loose valve springs - Change valve springs.
Valves are stuck - Service the valves.
Poor compression - Check and repair damaged parts.
Dirty fuel filter - Replace fuel filter.
Damaged or clogged fuel injector - Clean or replace if necessary.
Insufficient engine oil - Fill up the engine oil.
Faulty oil pump - Oil pump need to be replaced.
Clogged water intake - Wash or clean as required.
Damaged thermostat - Change thermostat as required.
Water pump failure - Install new water pump.
Defective ignition system - Inspect ignition system and change failed components.
Clogged or damaged fuel pump - Service or change fuel pump.
Worn or defective vapor separator needle valve - Change vapor separator needle valve.
Restricted fuel lines - Fuel lines must be clean.
Fuel tank air vent clogged or closed - Open or service air vent.
Fuel filter is dirty - Replace fuel filter.
Intake manifold is air leaking - Replace intake manifold gasket.
Water intake is clogged - Need to clean or wash.
Throttle valve and throttle link are damaged or worn - Change faulty parts.
Fuel injector is faulty or clogged - Clean or install new injector.
Excessive engine load - Load reducing is recommended.
Clogged fuel pump or fuel injector - Replace or clean if necessary.
Ignition timing is incorrect - Adjust ignition timing as required.
Thermostat failure - Change thermostat as required.
Damaged water pump - Replace water pump.
Propeller selection improperly - Check the propeller size.
Propeller bent or damaged - Replace propeller.
Outboard motor is positioned too low or too high - Position the engine correctly.
Engine oil level is insufficient - Checking oil level and add if necessary.
Oil pump malfunction - Oil pump need to be replaced.
Water intake screen is dirty - Need to clean or wash.
Improper valve setting - Adjust valves as required.
| Abnormal engine knocking or noise |
Low octane gasoline - Use correct gasoline.
Excessive engine load - Load reducing required.
Incorrectly adjusted low idle speed - Adjust the low idle speed.
Dirty or damaged fuel pump - Test fuel pump and change if necessary.
Crankshaft or main bearings wear - Worn parts replacement required.
Cylinder bore or piston rings are worn - Replace defective components.
Clogged fuel lines - Fuel lines must be clean.
Defective fuel injector - Change fuel injector.
Fuel pump is dirty or defective - Service or change fuel pump.
Ignition system is defective - Inspect ignition system and change failed components.
Cylinder head gasket is blown - Replace the head gasket.
Worn powerhead parts - Replace defective parts.
Burned or stuck valves - Clean or replace valves.
Improper propeller diameter or pitch - Install correct propeller.
Propeller bent or damaged - Replace propeller.
Outboard motor mounting height is set incorrectly - Check the outboard motor mounting height.
Improper trim angle - Adjust trim angle.
| Engine using too much gasoline |
Fuel injector is clogged or malfunction - Clean or install new injector.
Spark plug is loose or faulty - Tighten or change the spark plug.
Rings, sleeve, or piston are damaged - Replace defective parts as required.
ECU is faulty - Install new ECU.
| Motor vibrates excessively |
Propeller bent or damaged - Replace propeller.
Propeller shaft malfunction - Replace propeller shaft.
Weeds in the propeller - Clean the propeller.
Engine mounting bolt is not tightened - Tighten the bolt as required.
Steering pivot is faulty or loose Tighten correctly or replace.
Low battery output - Battery is drained, charge it.
Battery discharges quickly - Service charging system or install new battery.
Bad terminals or disconnected battery cables - Check wire connections and change or service terminals.
Starter motor is damaged - Starter needs to be changed.
| Trim motor runs but trim system does not move up or down |
Not enough oil - Fill up oil to required level.
Pump assembly is damaged - Inspect pump and change as required.
Leakage of manual release valve - Close the valve or change it.
Broken motor or pump driveshaft - Change worn component.
| Trim does not fully up or down |
Pump assembly faulty - Change pump.
Tilt ram piston ball is in wrong position - Service or repair.
Tilt ram piston O-ring is worn - Change O-ring.
Not enough oil - Checking oil level and add if necessary.
Lower check valve is not properly secured in port side trim ram - Secure valve properly.
____________________________________________________________________________________
| Outboard Engines Technical Specifications |
| Small Engines Technical Specifications |
| Car Engines Technical Specifications |
| Industrial Engines Technical Specifications |
