Yamaha F70LA Troubleshooting
| Engine Model: Yamaha F70LA |
| Engine Type: 4-stroke inline 4-cylinder SOHC 16-valve gasoline outboard engine |
| Total Displacement: 60.8 cu.in (996 cc) |
| Rated Engine Power: 70 Hp (51.5 kW) at 5800 rpm |
| Fuel System: Electronic Fuel Injection (EFI) |
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| Engine hard to start or doesn't start |
No gasoline in tank - Add fuel.
Wrong fuel grade - Use correct gasoline grade.
Air in fuel tank - Bleed fuel tank.
Spark plug wiring connection is damaged - Inspect the spark plug wire connection, replace or repair.
Faulty spark plug - Change spark plug.
Fuel filter is plugged - Fuel filter needs to be replaced.
Damaged or wear vapor separator needle valve - Replace needle valve.
Restricted fuel lines - Service fuel lines.
Fuel tank air vent clogged or closed - Open or service air vent.
Fuel feed pump failure - Install new feed pump or repair it.
Choke cable is worn or not adjusted properly - Adjust properly or replace the cable.
Valve clearance is improper - Need to adjust valve clearance.
Valve timing is incorrect - Set the valve timing properly.
Low fuel pressure - Inspect low pressure fuel pump or inspect fuel system for leaks.
Fuel injector is faulty or clogged - Clean or install new injector.
Fuel regulator is defective - Install new fuel regulator.
ECM is not functioning - Change electronic control modul.
| Engine starts and stalls suddenly |
Spark plug is faulty - Change spark plug.
Worn or defective vapor separator needle valve - Replace needle valve.
Defective ignition coil - Change ignition coil as required.
Fuel tank air vent clogged or closed - Open or service air vent.
Defective fuel pump - Repair or change fuel pump.
Faulty choke system - Check and repair choke system.
Excessive valve clearance - Adjust valve clearance according to specifications.
Valve timing is improper - Set the valve timing properly.
Broken or loose valve springs - New valve springs need to be installed.
Valves are stuck - Valves must be cleaned.
Low cylinder compression - Check and change damaged parts.
Fuel filter is plugged - Replace or clean fuel filter.
Fuel injector is faulty or clogged - Replace or clean as required.
Not enough engine oil - Check and refill engine oil.
Defective oil pump - Change oil pump as required.
Water intake screen is dirty - Wash or clean as required.
Thermostat failure - Change thermostat.
Damaged water pump - Water pump need to be replaced.
| Engine runs intermittently |
Ignition system is defective - Check ignition system and replace faulty parts.
Dirty or defective fuel pump - Inspect fuel pump and change as required.
Worn or defective vapor separator needle valve - Replace needle valve.
Fuel lines are clogged - Service fuel lines.
Fuel tank air vent restricted or closed - Open or clean air vent.
Dirty fuel filter - Replace fuel filter.
Intake manifold air leaks - Install new gasket.
Water intake screen is dirty - Wash or clean as required.
Throttle valve and throttle link are defective or worn - Change faulty parts.
Clogged or worn fuel injector - Replace or clean as required.
Engine overloaded - Reduce the load.
Fuel pump or fuel injector is dirty - Clean or replace as required.
Ignition timing is improper - Ignition timing needs to be adjusted correctly.
Thermostat is defective - Change thermostat as required.
Defective water pump - Change water pump.
Propeller selection improperly - Install correct propeller.
Damaged or bent propeller - Replace propeller.
Outboard engine is positioned too low or too high - Position the engine correctly.
Insufficient engine oil - Fill up the engine oil.
Oil pump failure - Change oil pump.
Dirty water intake screen - Need to wash or clean.
Valve setting is wrong - Adjust valves as required.
Low octane gasoline - Use proper gasoline.
Engine overload - Load reducing required.
Low idle speed adjustment is incorrect - Correct idle adjustment.
Fuel pump is clogged or faulty - Check fuel pump and change if required.
Main bearings or crankshaft are worn out - Need to install new components.
Damaged piston rings or cylinder bore - Change defective parts.
Fuel lines clogging - Fuel lines must be clean.
Damaged fuel injector - Install new fuel injector.
Fuel pump is faulty or clogged - Test fuel pump and change if necessary.
Ignition failure - Inspect ignition system and change faulty parts.
Cylinder head gasket is damaged - Install new head gasket.
Powerhead components are damaged - Change defective parts.
Valves are burned or stuck - Replace or clean valves.
Incorrect propeller selection - Install correct propeller.
Damaged or bent propeller - Have propeller repaired or replaced.
Outboard engine mounting height improperly - Check the outboard engine mounting height.
Trim angle is incorrect - Adjust trim angle.
| Engine uses too much fuel |
Dirty or faulty fuel injector - Clean or replace as required.
Loose or faulty spark plug - Spark plug need to be replaced or tightened.
Sleeve, rings, or piston are damaged - Replace defective parts.
ECU is not functioning - Change electronic control unit.
| Excessive engine vibration |
Damaged or bent propeller - Have propeller repaired or replaced.
Propeller shaft malfunction - Propeller shaft needs to be replaced.
Weeds wraped around propeller - Clean the propeller.
Engine mounting bolt is not tightened - Tighten bolt.
Damaged or loose steering pivot Tighten correctly or replace.
Low battery output voltage - Low battery charging, charge as required.
Battery won’t hold charge - Service or change the battery.
Wires are disconnected or battery terminals are corroded - Connect wiring properly or install new terminals.
Starter motor is defective - Replace or repair starter.
| Trim motor runs but trim system does not move up or down |
Insufficient oil - Need to add the oil.
Pump assembly is damaged - Inspect pump and change as required.
Manual shut-off valve leaks - Close the valve or change it.
Broken motor or pump driveshaft - Change defective component.
| Trim cannot be fully up or down |
Pump assembly faulty - Replace pump.
Tilt ram piston ball is not positioned correctly - Clean or repair.
Worn tilt ram piston O-ring - Change O-ring.
Insufficient oil - Need to add the oil.
Lower check valve is not properly secured in port side trim ram - Install valve correctly.
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