Yamaha F70LB Troubleshooting
| Engine Model: Yamaha F70LB |
| 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 will not start or difficult to start |
Fuel tank is empty - Fill it up.
Improper fuel grade - Use correct gasoline grade.
Air in the fuel system - Air bleeding.
Loose or disconnected spark plug wire - Check spark plug wiring connection, repair or change.
Spark plug is defective - Change spark plug as required.
Plugged fuel filter - Change fuel filter.
Vapor separator needle valve is bend or wear - Install new needle valve.
Restricted fuel lines - Fuel lines need to be cleaned.
Closed or restricted fuel tank air vent - Open or service air vent.
Defective fuel feed pump - Replace or repair fuel pump.
Choke cable is not adjusted properly or worn - Adjust correctly or replace the cable.
Valve clearance is improper - Adjust to proper valve clearance.
Improper valve timing - Set the valve timing correctly.
Low fuel pressure - Inspect fuel system for leaks or inspect low pressure fuel pump.
Fuel injector is damaged or dirty - Clean or replace if necessary.
Fuel regulator is faulty - Install new fuel regulator.
ECM is faulty - Replace ECM.
| Engine starts and stalls immediately |
Spark plug is defective - Change spark plug.
Vapor separator needle valve is bend or wear - Replace needle valve.
Defective ignition coil - Replace ignition coil as necessary.
Fuel tank air vent clogged or closed - Fuel tank air vent need to be opened or cleaned.
Fuel pump malfunction - Replace or repair fuel pump.
Choke system malfunction - Change choke system components as required.
Improper valve clearance - Adjust valve clearance.
Valve timing is incorrect - Set the valve timing properly.
Damaged or weak valve springs - Install new valve springs.
Valves sticking - Service the valves.
Low compression - Check and repair damaged parts.
Dirty fuel filter - Change fuel filter.
Fuel injector is faulty or clogged - Clean or replace if necessary.
Not enough engine oil - Fill up the oil to required level.
Defective oil pump - Oil pump need to be replaced.
Water intake is clogged - Clean and wash as required.
Thermostat failure - Change thermostat.
Water pump is defective - Replace water pump.
Ignition failure - Check ignition and replace faulty components.
Clogged or damaged fuel pump - Test fuel pump and replace if necessary.
Vapor separator needle valve is damaged or worn - Replace needle valve.
Fuel lines are clogged - Clean fuel lines.
Closed or restricted fuel tank air vent - Open or clean air vent.
Plugged fuel filter - Install new filter.
Intake manifold air leaks - Install new gasket.
Water intake is blocked - Clean and wash as required.
Throttle valve and throttle link are damaged or worn - Replace faulty parts.
Fuel injector is clogged or malfunction - Clean or replace if necessary.
Engine is running overloaded - Reduce the load.
Fuel pump or fuel injector is clogged - Clean or replace if necessary.
Ignition timing is wrong - Set the ignition timing properly.
Damaged thermostat - Replace thermostat.
Damaged water pump - Change water pump.
Incorrect propeller selection - Replace propeller.
Damaged or improper size of propeller - Replace propeller.
Outboard engine is mounted too high or too low - Position the engine correctly.
Low engine oil level - Fill up the engine oil.
Damaged oil pump - Change oil pump.
Water intake is blocked - Wash or clean as required.
Improper valve setting - Set the valves correctly.
Stale gasoline - Use correct gasoline.
Engine overload - Load reducing is recommended.
Incorrect low idle setting - Adjust idling as required.
Fuel pump is dirty or defective - Check fuel pump and change if required.
Worn main bearings or crankshaft - Have bearings or crankshaft replaced.
Damaged piston rings or cylinder bore - Replace defective components.
Restricted fuel lines - Service fuel lines.
Damaged fuel injector - Replace fuel injector.
Clogged or damaged fuel pump - Test fuel pump and replace if necessary.
Ignition failure - Inspect ignition system and change faulty parts.
Damaged cylinder head gasket - Replace the head gasket.
Powerhead components are faulty - Change defective parts.
Valves are stuck or burned - Change or clean valves.
Propeller pitch or diameter incorrect - Replace propeller.
Propeller bent or damaged - Have propeller repaired or replaced.
Outboard engine mounting height improperly - Check the outboard engine mounting height.
Incorrect trim angle - Adjust trim angle correctly.
| Engine using too much gasoline |
Fuel injector is clogged or malfunction - Replace or clean if necessary.
Loose or faulty spark plug - Tighten or change the spark plug.
Worn sleeve, rings, or piston - Replace faulty parts.
ECU is faulty - Replace ECU.
| Engine vibrates excessively |
Propeller bent or damaged - Have propeller repaired or replaced.
Propeller shaft malfunction - Propeller shaft needs to be replaced.
Weeds wraped around propeller - Remove and clean propeller.
Motor mounting bolt is loose - Tighten bolt.
Damaged or loose steering pivot Tighten or replace.
Battery power is low - Battery needs to be recharged.
Battery is draining quickly - Service or change the battery.
Faulty battery terminals or disconnected cables - Check wiring connections and replace or clean terminals.
Defective starter motor - Starter needs to be replaced.
| Trim motor runs but trim system does not move up or down |
Oil level is low - Check and refill oil.
Pump assembly is damaged - Inspect pump and change as required.
Manual release valve leaking - Close the valve or change it.
Faulty pump driveshaft or motor - Replace worn component.
| Trim cannot be fully up or down |
Damaged pump assembly - Replace pump.
Tilt ram piston ball is not positioned correctly - Clean or repair.
Worn tilt ram piston O-ring - Change O-ring.
Oil level is insufficient - Fill up oil to required level.
Lower check valve is not properly secured in port side trim ram - Install valve correctly.
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