Yamaha F70A Troubleshooting
| Engine Model: Yamaha F70A |
| 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) |
____________________________________________________________________________________
| Engine doesn't start or hard to start |
No gasoline in tank - Add gasoline.
Wrong grade of gasoline - Use correct gasoline grade.
Clogged fuel system - Remove clogging.
Defective wiring connection of spark plug - Check spark plug wiring connection, repair or change.
Damaged spark plug - Change spark plug.
Fuel filter is dirty - Replace or clean fuel filter.
Vapor separator needle valve is damaged or worn - Install new needle valve.
Fuel lines are dirty - Clean fuel system lines.
Fuel tank air vent clogged or closed - Fuel tank air vent need to be opened or cleaned.
Damaged fuel feed pump - Change or rebuild fuel feed pump.
Throttle cable is damaged or adjusted incorrectly - Adjust correctly or change the cable.
Excessive valve clearance - Adjust valve clearance.
Wrong valve timing - Adjust valve timing as required.
Low fuel pressure - Check system for fuel leaks or check low pressure fuel pump.
Clogged or worn fuel injector - Clean or replace if necessary.
Fuel regulator failure - Replace fuel regulator.
ECM failure - Install new ECM.
| Engine starts but stalls immediately |
Spark plug is defective - Install new spark plug.
Worn or defective vapor separator needle valve - Install new needle valve.
Ignition coil is damaged - Change ignition coil as required.
Closed or restricted fuel tank air vent - Open or service air vent.
Fuel pump malfunction - Replace or repair fuel pump.
Choke system malfunction - Check and repair choke system.
Excessive valve clearance - Adjustment procedure required.
Valve timing is improper - Set the valve timing properly.
Valve springs are weak or broken - Valve springs need to be changed.
Valves are stuck - Valves need to be cleaned.
Poor cylinder compression - Check and replace worn parts.
Fuel filter is dirty - Fuel filter needs to be replaced.
Damaged or clogged fuel injector - Clean or install new injector.
Insufficient engine oil - Need to add engine oil.
Oil pump failure - Oil pump need to be replaced.
Water intake is blocked - Need to wash or clean.
Faulty thermostat - Thermostat need to be replaced.
Water pump failure - Water pump need to be replaced.
Ignition system problems - Inspect ignition system and change failed components.
Fuel pump is faulty or clogged - Service or change fuel pump.
Vapor separator needle valve is worn or defective - Install new needle valve.
Dirt in the fuel lines - Clean fuel lines.
Closed or clogged fuel tank air vent - Fuel tank air vent need to be opened or cleaned.
Dirty fuel filter - Change fuel filter.
Intake manifold air leaks - Change intake manifold gasket.
Water intake is clogged - Wash or clean as required.
Throttle link and throttle valve are wear or damaged - Replace faulty components.
Dirty or faulty fuel injector - Clean or replace as required.
Engine is running overloaded - Reduce load.
Clogged fuel pump or fuel injector - Replace or clean as required.
Improper ignition timing - Adjust ignition timing as required.
Defective thermostat - Change thermostat.
Damaged water pump - Water pump need to be replaced.
Propeller pitch or diameter incorrect - Install correct propeller.
Damaged or improper size of propeller - Replace propeller.
Outboard motor is positioned too low or too high - Position the engine correctly.
Engine oil insufficient - Check oil level and add oil as required.
Oil pump failure - Replace oil pump.
Clogged water intake - Need to clean or wash.
Valve setting is wrong - Adjust valves as required.
Stale or low octane fuel - Change fuel.
Engine overload - Load reducing required.
Incorrectly set low idle speed - Adjust idling as required.
Clogged or damaged fuel pump - Clean or change fuel pump.
Crankshaft or main bearings wear - Have bearings or crankshaft replaced.
Piston rings or cylinder bore are damaged - Change defective parts.
Dirt in the fuel lines - Clean fuel lines.
Damaged fuel injector - Replace fuel injector.
Dirty or faulty fuel pump - Clean or install new fuel pump.
Ignition system malfunction - Inspect ignition system and change failed components.
Damaged cylinder head gasket - Cylinder-head gasket replacement required.
Worn powerhead parts - Defective components need to be replaced.
Valves are burned or stuck - Service or replace valves.
Improper propeller diameter or pitch - Replace propeller.
Damaged or improper size of propeller - Replace propeller.
Motor mounted at incorrect height on transom - Have motor adjusted to proper transom height.
Trim angle is incorrect - Adjust trim angle.
| Excessive fuel consumption |
Damaged or clogged fuel injector - Clean or replace as required.
Defective or loose spark plug - Re-tighten or replace spark plug.
Rings, sleeve, or piston are damaged - Replace faulty components as required.
ECU is not functioning - Change electronic control unit.
| Engine vibrates excessively |
Damaged or bent propeller - Replace propeller.
Propeller shaft damaged - 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.
Battery power is low - Recharge the battery.
Battery discharges quickly - Service battery or replace it.
Disconnected wires or corroded battery terminals - Check wiring and clean or replace terminals.
Starter motor failure - Change or repair starter.
____________________________________________________________________________________
| Outboard Engines Technical Specifications |
| Small Engines Technical Specifications |
| Car Engines Technical Specifications |
| Industrial Engines Technical Specifications |
