Yamaha F70AETL Troubleshooting
| Engine Model: Yamaha F70AETL |
| 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 starts up hard or will not start |
Empty gas tank - Fill it up.
Incorrect fuel grade - Change fuel.
Air or water in fuel system - Remove water or air from fuel system.
Spark plug wire is loose or disconnected - Inspect spark plug wiring connection, change or repair.
Spark plug is defective - Install new spark plug.
Fuel filter is clogged - Change fuel filter.
Vapor separator needle valve is bend or wear - Replace needle valve.
Fuel lines are dirty - Clean fuel lines.
Closed or restricted fuel tank air vent - Open or clean air vent.
Damaged fuel feed pump - Change or rebuild fuel feed pump.
Choke cable is not adjusted properly or worn - Adjust properly or replace the cable.
Valve clearance is wrong - Adjust valve clearance according to specifications.
Valve timing is incorrect - Set the valve timing correctly.
Low fuel pressure - Check low pressure fuel pump or check system for fuel leaks.
Fuel injector is faulty or clogged - Clean or replace if necessary.
Fuel regulator malfunction - Replace fuel regulator.
ECM is faulty - Replace ECM.
| Engine starts but then stalls |
Spark plug is defective - Spark plug need to be replaced.
Damaged or wear vapor separator needle valve - Install new needle valve.
Ignition coil is faulty - Ignition coil must be replaced.
Fuel tank air vent closed or restricted - Open or service air vent.
Fuel pump defective - Replace or repair fuel pump.
Damaged choke system - Check and repair choke system.
Valve clearance is wrong - Check and adjust.
Improper valve timing - Set the valve timing properly.
Worn or loose valve springs - New valve springs need to be installed.
Valves sticking - Valves need to be cleaned.
Bad compression - Check and repair damaged parts.
Fuel filter is plugged - Fuel filter needs changing.
Fuel injector is dirty or worn - Clean or replace if necessary.
Lack of engine oil - Check and refill engine oil.
Defective oil pump - Oil pump need to be replaced.
Water intake screen is dirty - Wash or clean as required.
Thermostat is faulty - Thermostat need to be replaced.
Water pump is defective - Water pump need to be replaced.
Ignition system malfunction - Test ignition and replace failed parts.
Fuel pump is clogged or faulty - Check fuel pump and change if required.
Vapor separator needle valve is bend or wear - Replace needle valve.
Clogged 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.
Plugged fuel filter - Change fuel filter.
Intake manifold is air leaking - Replace intake manifold gasket.
Clogged water intake - Clean and wash as required.
Throttle valve and throttle link are damaged or worn - Replace faulty components.
Clogged or worn fuel injector - Replace or clean if necessary.
Excessive engine load - Reduce load.
Fuel injector or fuel pump is clogged - Clean or replace if necessary.
Wrong ignition timing - Adjust ignition timing as required.
Damaged thermostat - Thermostat need to be replaced.
Water pump is defective - Water pump need to be replaced.
Incorrect propeller selection - Check the propeller size.
Damaged or improper size of propeller - Have propeller repaired or replaced.
Outboard motor is positioned too low or too high - Position the engine correctly.
Not enough engine oil - Checking oil level and add if necessary.
Defective oil pump - Change oil pump as required.
Water intake screen is dirty - Wash or clean as required.
Incorrect valve setting - Adjust valves correctly.
| Abnormal engine noise or knocking |
Stale gasoline - Use proper fuel.
Excessive engine load - Load reducing is recommended.
Incorrectly set low idle speed - Adjust idling as required.
Fuel pump is faulty or clogged - Check fuel pump and change if required.
Crankshaft or main bearings failure - Replace crankshaft or bearings.
Damaged cylinder bore or piston rings - Change defective components.
Dirty fuel lines - Clean fuel system lines.
Damaged fuel injector - Replace fuel injector.
Fuel pump is damaged or dirty - Test fuel pump and change if necessary.
Defective ignition - Test ignition and replace failed parts.
Damaged cylinder head gasket - Cylinder-head gasket replacement required.
Powerhead parts are damaged - Defective components need to be replaced.
Valves are stuck or burned - Clean or replace valves.
Propeller selection improperly - Install correct propeller.
Propeller bent or damaged - Replace propeller.
Motor mounted at incorrect height on transom - Adjust the outboard motor height correctly.
Incorrect trim angle - Adjust trim angle.
| Excessive fuel consumption |
Clogged or worn fuel injector - Replace or clean as required.
Loose or faulty spark plug - Tighten or replace spark plug.
Worn piston, rings, or sleeve - Replace defective components.
Electronic control unit failure - Replace ECU.
Propeller bent or damaged - Replace propeller.
Damaged propeller shaft - Propeller shaft needs to be replaced.
Weeds wraped around propeller - Remove weeds from propeller.
Engine mounting bolt is not tightened - Tighten bolt.
Damaged or loose steering pivot Tighten correctly or replace.
Battery voltage is low - Battery needs to be recharged.
Battery runs out quickly - Service or replace the battery.
Bad terminals or disconnected battery cables - Connect cables properly or replace terminals.
Starter motor failing - Starter should be changed.
| Trim motor runs but trim system does not move up or down |
Low oil level - Check oil level and add oil as required.
Damaged pump assembly - Check pump and change if required.
Leakage of manual drain valve - Valve need to be closed or changed.
Broken motor or pump driveshaft - Replace worn component.
| Trim cannot be fully up or down |
Pump assembly is defective - Change pump.
Tilt ram piston ball is displaced - Service or repair.
Tilt ram piston O-ring damaged - Change O-ring.
Oil level is low - Fill up oil.
Lower check valve is not properly secured in port side trim ram - Secure valve properly.
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