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Suzuki DF40ATL Troubleshooting
The Suzuki DF40ATL is a four-stroke three-cylinder double overhead camshaft gasoline long shaft outboard engine. This engine has a multi-point sequential electronic fuel injection, integral fuel pump, water cooled with thermostat, and full-transistorized ignition system. A 57.4 cu.in (941 cc) outboard motor has a cylinder bore of 2.85" (72.5 mm), piston stroke of 2.99" (76 mm), and maximum power of 40 hp (29.5 kW) at 5000-6000 rpm. The boat motor is equipped with an electric starting system, 3-blades aluminum standard propeller, power trim and tilt, and tiller handle or remote control steering system. The fuel tank has a capacity of 6.6 gal (25 liters).
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| Engine starts up hard or doesn't start |
Fuel tank is empty - Fill gasoline up.
Wrong fuel grade - Use quality fuel.
Air or water in fuel system - Remove water or air from fuel system.
Loose or disconnected spark plug wire - Check spark plug wiring connection, repair or change.
Spark plug is defective - Spark plug need to be replaced.
Plugged fuel filter - Change fuel filter.
Worn or defective vapor separator needle valve - Replace needle valve.
Fuel lines are dirty - Service fuel lines.
Fuel tank air vent closed or restricted - Fuel tank air vent need to be opened or cleaned.
Fuel feed pump defective - Install new feed pump or repair it.
Incorrectly adjusted or damaged throttle cable - Replace cable or adjust correctly.
Incorrect valve clearance - Check and adjust.
Improper valve timing - Adjust valve timing correctly.
Fuel pressure is low - Inspect fuel system for leaks or inspect low pressure fuel pump.
Fuel injector is dirty or worn - Clean or install new injector.
Fuel regulator is defective - Install new fuel regulator.
ECM is not functioning - Install new ECM.
| Engine starts and stops suddenly |
Spark plug is faulty - Change spark plug as required.
Worn or defective vapor separator needle valve - Change vapor separator needle valve.
Ignition coil is defective - Change ignition coil as required.
Fuel tank air vent restricted or closed - Open or service air vent.
Defective fuel pump - Repair or change fuel pump.
Damaged choke system - Change choke system components as required.
Improper valve clearance - Adjust valve clearance.
Wrong valve timing - Adjust valve timing correctly.
Weak or damaged valve springs - Install new valve springs.
Valves sticking - Valves must be cleaned.
Bad cylinder compression - Check and change damaged parts.
Plugged fuel filter - Fuel filter needs changing.
Dirty or faulty fuel injector - Replace or clean if necessary.
Engine oil level is low - Check oil level and add oil as required.
Defective oil pump - Change oil pump.
Water intake is blocked - Wash or clean as required.
Thermostat is defective - Replace thermostat.
Faulty water pump - Install new water pump.
| Engine runs unevenly |
Defective ignition system - Test ignition and replace failed parts.
Fuel pump is defective or dirty - Clean or change fuel pump.
Worn or defective vapor separator needle valve - Change vapor separator needle valve.
Restricted fuel lines - Clean fuel system lines.
Closed or restricted fuel tank air vent - Fuel tank air vent need to be opened or cleaned.
Fuel filter is dirty - Fuel filter needs changing.
Intake manifold air leaks - Change intake manifold gasket.
Dirty water intake screen - Wash or clean as required.
Throttle link and throttle valve are worn or damaged - Change faulty parts.
Damaged or clogged fuel injector - Replace or clean if necessary.
| Engine overheating |
Engine is running overloaded - Reduce engine load.
Fuel pump or fuel injector is clogged - Replace or clean if necessary.
Ignition timing is improper - Adjust ignition timing correctly.
Thermostat is defective - Replace thermostat.
Faulty water pump - Replace water pump.
Improper propeller diameter or pitch - Install correct propeller.
Damaged or improper size of propeller - Have propeller repaired or replaced.
Outboard engine is mounted too high or too low - Mount the motor as required.
Not enough engine oil - Fill up the oil to required level.
Damaged oil pump - Install new oil pump.
Water intake is blocked - Wash or clean as required.
Improper valve setting - Set the valves correctly.
| Abnormal engine noise or knocking |
Low octane gasoline - Use correct gasoline.
Engine is overloaded - Reduce load.
Incorrect low idle setting - Correct idle adjustment.
Fuel pump is defective or dirty - Clean or install new fuel pump.
Crankshaft or main bearings failure - Change or repair worn components.
Worn piston rings or cylinder bore - Replace faulty components.
| Engine power is insufficient |
Restricted fuel lines - Service fuel lines.
Fuel injector is fault - Change fuel injector.
Fuel pump is dirty or defective - Clean or install new fuel pump.
Ignition failure - Check ignition and replace faulty components.
Cylinder head gasket is defective - Replace the gasket as required.
Powerhead components are faulty - Replace defective components.
Valves are burned or stuck - Service or replace valves.
Propeller pitch or diameter incorrect - Replace propeller.
Damaged or bent propeller - Have propeller repaired or replaced.
Outboard motor mounting height is set incorrectly - Check the outboard engine mounting height.
Trim angle is incorrect - Make the correct trim angle adjustment.
| High fuel consumption |
Fuel injector is damaged or dirty - Clean or install new injector.
Defective or loose spark plug - Spark plug need to be replaced or tightened.
Worn sleeve, rings, or piston - Change faulty parts.
Electronic control unit is not operating - Change electronic control unit.
| Motor vibrates excessively |
Damaged or improper size of propeller - Have propeller repaired or replaced.
Damaged propeller shaft - Propeller shaft needs to be replaced.
Weeds wraped around propeller - Remove weeds from propeller.
Motor mounting bolt is loose - Tighten bolt.
Damaged or loose steering pivot Tighten or replace.
| Starter will not work |
Low battery power - Charge the battery.
Battery does not hold charge - Service battery or replace it.
Bad battery terminals or disconnected wiring - Connect wires correctly or change terminals.
Starter motor is defective - Starter should be changed.
| Trim motor runs but trim system does not move up or down |
Oil level low - Fill up oil.
Defective pump assembly - Check pump and change if required.
Leakage of manual release valve - Close the valve fully or replace it.
Faulty pump driveshaft or motor - Replace worn component.
| Trim cannot be fully up or down |
Damaged pump assembly - Change pump as required.
Tilt ram piston ball is in wrong position - Service or repair.
Damaged tilt ram piston O-ring - Change O-ring.
Low oil level - Fill up oil to required level.
Lower check valve not seating in port side trim ram - Install valve correctly.
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