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Mercury EFI 200 Troubleshooting

Engine Model: Mercury EFI 200 Hp
Engine Type: 2-cycle 6-cylinder gasoline outboard engine
Total Displacement: 153 (2507 cc)
Rated Engine Power: 200 Hp (149.1 kW) at 5750 rpm
Fuel System: Electronic fuel injection (EFI)


Engine starts hard or doesn't start

Empty fuel tank - Add fuel.
Wrong grade of gasoline - Use correct gasoline grade.
Air trapped in fuel system - Bleed air.
Loose or disconnected spark plug wire - Inspect the spark plug wire connection, replace or repair.
Defective spark plug - Replace spark plug.
Fuel filter is clogged - Install new filter.
Dirty fuel lines - Service fuel lines.
Discharged or faulty battery - Replace or charge as required.
Bad harness connections - Check electrical wire harness connections.
Ignition system failure - Check ignition system components and change if necessary.
Pulse fuel pump is defective - Pulse fuel pump need to be replaced.
Defective electric fuel pump - Change electric fuel pump as required.
Electronic control modul failure - Replace ECM.

Engine stops after starting

Damaged spark plug - Install new spark plug.
Faulty ignition coil - Change ignition coil as required.
Defective pulse fuel pump - Change pulse fuel pump.
Fuel system is clogged - Fuel system need to be cleaned.
Final fuel filter is clogged - Final filter needs changing.
Electric fuel pump is defective - Electric fuel pump need to be replaced.

Irregular engine running

Defective ignition - Inspect ignition system and change faulty parts.
Fuel pump is defective or dirty - Check fuel pump and change if required.
Dirt in the fuel lines - Clean fuel system lines.
Fuel filter is plugged - Fuel filter needs to be replaced.

Engine overheats

Excessive engine load - Reduce the load.
Improper ignition timing - Ignition timing needs to be set properly.
Defective thermostat - Thermostat need to be replaced.
Water pump is defective - Install new water pump.

Engine knocking sound or abnormal noise

Stale gasoline - Use proper gasoline.
Excessive engine load - Reduce load.
Low idle speed setting is incorrect - Adjust idling as required.
Fuel pump is defective or dirty - Test fuel pump and replace if necessary.
Main bearings or crankshaft wear - Worn parts replacement required.
Worn cylinder bore or piston rings - Replace defective parts.

Loss of engine power

Fuel pump is clogged or faulty - Check fuel pump and change if required.
Ignition system is defective - Test ignition and replace failed parts.
Worn powerhead parts - Change defective components.
Stator, coil, or switch box defective - Change faulty components.
Low compression - Correct.
Fuel delivery problem - Check fuel system.
Manifold is leaking - Leak must be repaired.
Vapor separator is flooded - Normalize vapor separator functions.

High fuel consumption

Defective or loose spark plug - Spark plug need to be replaced or tightened.
Worn sleeve, rings, or piston - Replace faulty parts as required.
Excessive engine load - Reduce the load.
Fuel injectors are defective or dirty - Service or change fuel injectors.

Trim motor runs but system does not move

Lack of oil - Need to add the oil.
Damaged pump assembly - Inspect pump and change as required.
Leakage of manual release valve - Close the valve or change it.
Faulty pump driveshaft or motor - Replace defective component.

Trim cannot be fully up or down

Pump assembly is faulty - Change pump.
Tilt ram piston ball is not positioned correctly - Service or repair.
Damaged tilt ram piston O-ring - Change O-ring.
Oil insufficient - Fill up oil to required level.
Lower check valve is not properly secured in port side trim ram - Secure valve properly.