Suzuki DF300B Troubleshooting
| Engine Model: Suzuki DF300B |
| Engine Type: 4-stroke 6-cylinder DOHC 24-valve gasoline outboard engine |
| Total Displacement: 267.9 cu.in (4.4 L) |
| Rated Engine Power: 300 Hp (220.7 kW) at 6000 rpm |
| Fuel System: Multi point sequential electronic fuel injection |
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| Engine will not start or difficult to start |
Empty gas tank - Fill gasoline up.
Wrong grade of gasoline - Use quality gasoline.
Fuel system clogged - Repair or replace.
Damaged spark plug wiring connection - Inspect the spark plug wire connection, replace or repair.
Spark plug is defective - Change spark plug as required.
Fuel filter is dirty - Fuel filter needs to be replaced.
Vapor separator needle valve is worn or defective - Install new needle valve.
Clogged fuel lines - Service fuel lines.
Fuel tank air vent closed or restricted - Open or service air vent.
Fuel feed pump defective - Change or rebuild fuel feed pump.
Unadjusted or worn throttle cable - Adjust properly or replace the cable.
Incorrect valve clearance - Adjust to proper valve clearance.
Wrong valve timing - Set the valve timing correctly.
Fuel pressure is low - Inspect low pressure fuel pump or inspect fuel system for leaks.
Fuel injector is faulty or clogged - Replace or clean as required.
Fuel regulator malfunction - Install new fuel regulator.
ECM is not functioning - Replace ECM.
Spark plug is faulty - Change spark plug as required.
Worn or defective vapor separator needle valve - Install new needle valve.
Ignition coil is damaged - Install a new ignition coil.
Closed or clogged fuel tank air vent - Fuel tank air vent need to be opened or cleaned.
Fuel pump is faulty - Change or rebuild fuel pump.
Choke system is damaged - Inspect and replace choke system components.
Incorrect valve clearance - Check and adjust.
Valve timing is incorrect - Adjust valve timing as required.
Damaged or weak valve springs - New valve springs need to be installed.
Valves sticking - Service the valves.
Bad cylinder compression - Check and replace worn parts.
Dirty fuel filter - Fuel filter needs changing.
Fuel injector is damaged or dirty - Clean or replace as required.
Lack of engine oil - Checking oil level and add if necessary.
Oil pump failure - Oil pump need to be replaced.
Dirty water intake screen - Need to clean or wash.
Damaged thermostat - Install new thermostat.
Faulty water pump - Change water pump as required.
Ignition system problems - Test ignition and replace failed parts.
Dirty or damaged fuel pump - Clean or replace fuel pump.
Vapor separator needle valve is worn or defective - Change vapor separator needle valve.
Dirt in the fuel lines - Service fuel lines.
Fuel tank air vent clogged or closed - Fuel tank air vent need to be opened or cleaned.
Fuel filter is plugged - Fuel filter needs to be replaced.
Intake manifold is air leaking - Change intake manifold gasket.
Water intake is blocked - Wash or clean as required.
Throttle link and throttle valve are worn or damaged - Replace faulty components.
Fuel injector is damaged or dirty - Clean or replace if necessary.
Engine is running overloaded - Reduce engine load.
Fuel injector or fuel pump is dirty - Clean or replace if necessary.
Bad ignition timing - Set the ignition timing properly.
Thermostat is defective - Change thermostat.
Water pump failure - Replace water pump.
Improper propeller diameter or pitch - Replace propeller.
Propeller bent or damaged - Replace propeller.
Outboard engine is mounted too high or too low - Position the engine correctly.
Engine oil insufficient - Checking oil level and add if necessary.
Oil pump is defective - Change oil pump as required.
Water intake screen is dirty - Wash or clean as required.
Valve setting is improper - Valves needs to be set correctly.
| Abnormal engine noise or knocking |
Stale or low octane fuel - Use correct fuel.
Engine overload - Load reducing is recommended.
Incorrect low idle setting - Adjustment required.
Fuel pump is damaged or dirty - Clean or replace fuel pump.
Crankshaft or main bearings wear - Install new parts as as required.
Cylinder bore or piston rings are worn - Change defective parts.
Fuel lines are clogged - Fuel lines must be clean.
Faulty fuel injector - Replace fuel injector.
Clogged or damaged fuel pump - Test fuel pump and change if necessary.
Defective ignition system - Inspect ignition system and change faulty parts.
Damaged cylinder head gasket - Change cylinder head gasket.
Damaged powerhead components - Change defective components.
Valves are burned or stuck - Replace or clean valves.
Improper propeller diameter or pitch - Replace propeller.
Propeller bent or damaged - Replace propeller.
Outboard engine mounting height improperly - Check the outboard motor mounting height.
Incorrect trim angle - Make the correct trim angle adjustment.
| Engine using too much gasoline |
Fuel injector is damaged or dirty - Clean or replace if necessary.
Spark plug is loose or faulty - Tighten or replace spark plug.
Worn rings, piston, or sleeve - Replace defective components as required.
Electronic control unit failure - Change electronic control unit.
| Excessive engine vibration |
Damaged or improper size of propeller - Replace propeller.
Propeller shaft malfunction - Replace propeller shaft.
Weeds in the propeller - Remove weeds from propeller.
Motor mounting bolt is loose - Tighten bolt.
Loose or faulty steering pivot Tighten correctly or replace.
Low battery power - Battery needs to be recharged.
Battery won’t hold charge - Service charging system or replace battery.
Disconnected wiring or bad battery terminals - Connect wiring properly or install new terminals.
Defective starter motor - Starter should be changed.
| Trim motor is running but trim system cannot move up or down |
Insufficient oil - Check and refill oil.
Pump assembly is damaged - Test pump and change if necessary.
Leakage of manual release valve - Valve need to be closed or changed.
Faulty pump driveshaft or motor - Change defective component.
| Trim does not fully up or down |
Pump assembly is defective - Change pump.
Tilt ram piston ball is displaced - Clean or repair.
Worn tilt ram piston O-ring - Replace O-ring.
Insufficient oil - Check and refill oil.
Lower check valve not seating in port side trim ram - Install valve correctly.
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