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Suzuki DF15AS Troubleshooting
The Suzuki DF15AS is a four-stroke two-cylinder overhead cam gasoline short shaft outboard engine. This engine has a multi-point sequential electronic fuel injection, integral fuel pump, water cooled with thermostat, and capacitor discharge ignition system. A 20.1 cu.in (327 cc) outboard motor has a cylinder bore of 2.38" (60.4 mm), piston stroke of 2.24" (57 mm), and maximum power of 15 hp (11 kW) at 5000-6000 rpm. The boat motor is equipped with a manual or electric starting system, 3-blades aluminum standard propeller, manual or power trim and tilt, and tiller handle or remote control steering system. The fuel tank has a capacity of 3.2 gal (12 liters).
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| Engine difficult to start or doesn't start |
Gas tank is empty - Add gasoline.
Wrong grade of gasoline - Use quality fuel.
Air in fuel system - Bleed fuel system.
Disconnected or loose spark plug wire - Check spark plug wiring connection, repair or change.
Spark plug is damaged - Install new spark plug.
Fuel filter is dirty - Replace fuel filter.
Vapor separator needle valve is worn or defective - Install new needle valve.
Restricted fuel lines - Fuel lines need to be cleaned.
Closed or restricted fuel tank air vent - Open or clean air vent.
Fuel feed pump malfunction - Replace or rebuild fuel feed pump.
Damaged or incorrectly adjusted choke cable - Adjust correctly or change the cable.
Valve clearance is not correct - Adjust to proper valve clearance.
Improper valve timing - Set the valve timing correctly.
Low fuel pressure - Inspect low pressure fuel pump or inspect fuel system for leaks.
Fuel injector is dirty or worn - Clean or replace as required.
Fuel regulator failure - Change fuel regulator.
ECM failure - Change electronic control modul.
| Engine starts but immediately stops |
Spark plug is defective - Change spark plug.
Vapor separator needle valve is damaged or worn - Replace needle valve.
Ignition coil is faulty - Ignition coil must be replaced.
Fuel tank air vent restricted or closed - Open or clean air vent.
Defective fuel pump - Change or rebuild fuel pump.
Choke system malfunction - Change choke system components as required.
Excessive valve clearance - Need to adjust valve clearance.
Improper valve timing - Adjust valve timing correctly.
Worn or loose valve springs - Replace valve springs.
Valves sticking - Service the valves.
Bad cylinder compression - Inspect and replace defective parts.
Dirty fuel filter - Install new filter.
Fuel injector is clogged or malfunction - Replace or clean as required.
Engine oil level is low - Checking oil level and add if necessary.
Defective oil pump - Install new oil pump.
Water intake screen is dirty - Need to wash or clean.
Defective thermostat - Change thermostat as required.
Water pump is defective - Change water pump as required.
| Rough engine running |
Ignition system is defective - Inspect ignition system and change faulty parts.
Fuel pump is dirty or defective - Check fuel pump and replace if necessary.
Worn or damaged vapor separator needle valve - Change vapor separator needle valve.
Dirt in the fuel lines - Clean fuel system lines.
Closed or clogged fuel tank air vent - Open or service air vent.
Fuel filter is dirty - Replace or clean fuel filter.
Intake manifold is air leaking - Install new gasket.
Clogged water intake - Need to wash or clean.
Throttle link and throttle valve are wear or damaged - Replace faulty parts.
Fuel injector is clogged or malfunction - Clean or install new injector.
| Engine is overheated |
Engine overloaded - Reduce engine load.
Fuel pump or fuel injector is dirty - Clean or replace as required.
Bad ignition timing - Ignition timing needs to be adjusted correctly.
Thermostat failure - Replace thermostat.
Water pump failure - Replace water pump.
Improper propeller diameter or pitch - Check the propeller size.
Propeller bent or damaged - Replace propeller.
Outboard motor is mounted too high or too low - Position the engine correctly.
Engine oil level is low - Fill up the engine oil.
Oil pump is defective - Change oil pump as required.
Dirty water intake screen - Need to clean or wash.
Incorrect valve setting - Adjust valves correctly.
| Engine knocking or noise |
Low octane fuel - Change fuel.
Engine is under excessive load - Reduce load.
Incorrectly adjusted low idle speed - Adjust idling as required.
Fuel pump is damaged or dirty - Clean or change fuel pump.
Main bearings or crankshaft wear - Replace crankshaft or bearings.
Piston rings or cylinder bore are worn - Change defective components.
| Engine power loss |
Dirt in the fuel lines - Clean fuel system lines.
Fuel injector is damaged - Check fuel injector and change if required.
Fuel pump is faulty or clogged - Test fuel pump and replace if necessary.
Ignition system failure - Check ignition and replace faulty components.
Cylinder head gasket is defective - Replace the head gasket.
Powerhead parts are damaged - Replace defective components as required.
Burned or stuck valves - Change or service valves.
Propeller selection improperly - Replace propeller.
Propeller bent or damaged - Have propeller repaired or replaced.
Outboard engine mounting height improperly - Adjust the outboard motor height correctly.
Improper trim angle - Adjust trim angle correctly.
| Excessive fuel consumption |
Fuel injector is dirty or worn - Replace or clean if necessary.
Faulty or loose spark plug - Change or re-tighten spark plug.
Worn sleeve, piston, or rings - Replace faulty parts.
Electronic control unit is not operating - Install new ECU.
| Strong engine vibration |
Damaged or bent propeller - Have propeller repaired or replaced.
Propeller shaft malfunction - Replace propeller shaft.
Weeds wraped around propeller - Clean the propeller.
Motor mounting bolt is loose - Tighten the bolt as required.
Steering pivot is faulty or loose Tighten correctly or replace.
| Starter does not work |
Battery voltage is low - Charge the battery.
Battery won’t hold charge - Service or change the battery.
Disconnected cables or faulty battery terminals - Connect wires correctly or change terminals.
Starter motor is defective - Starter should be changed.
| Trim motor is running but trim system cannot move up or down |
Not enough oil - Fill up oil.
Damaged pump assembly - Test pump and replace if necessary.
Manual release valve leaking - Close the valve or change it.
Pump driveshaft or motor damaged - Replace defective component.
| Trim cannot be fully up or down |
Defective pump assembly - Change pump as required.
Tilt ram piston ball is displaced - Clean or repair.
Damaged tilt ram piston O-ring - Replace O-ring.
Not enough 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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