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Mercury XR6 150 Troubleshooting

Engine Model: Mercury XR6 150 Hp
Engine Type: 2-cycle 6-cylinder gasoline outboard engine
Total Displacement: 153 (2507 cc)
Rated Engine Power: 150 Hp (111.8 kW) at 5500 rpm
Fuel System: Carburetor with adjustable jet


Engine hard to start or doesn't start

No gasoline in tank - Fill it up.
Incorrect fuel grade - Use correct fuel grade.
Air in fuel system - Bleed fuel system.
Spark plug wiring connection is defective - Check spark plug wiring connection, repair or change.
Spark plug is faulty - Install new spark plug.
Clogged fuel filter - Fuel filter needs to be replaced.
Carburetor problems - Carburetor diagnostics required.
Fuel lines are clogged - Fuel lines must be clean.
Closed or restricted fuel tank air vent - Open or service air vent.
Low fuel pump pressure - Install new pump or repair it.

Engine starts and stalls suddenly

Spark plug is defective - Change spark plug.
Carburetor is dirty or faulty - Repair or clean carburetor.
Faulty ignition coil - Change ignition coil as required.
Closed or restricted fuel tank air vent - Open or service air vent.
Lack of fuel pump pressure - Change or rebuild fuel pump.
Faulty thermal relief valve - Replace thermal relief valve.

Engine runs intermittently

Ignition system is defective - Inspect ignition system and change failed components.
Fuel pump is damaged or dirty - Inspect fuel pump and change as required.
Carburetor is dirty - Wash, clean and adjust.
Clogged fuel lines - Fuel lines must be clean.
Closed or restricted fuel tank air vent - Open or service air vent.
Fuel filter is dirty - Fuel filter needs to be replaced.
Gaskets are defective - Replace gaskets.

Engine is overheated

Engine is running overloaded - Reduce the load.
Carburetor is running lean - Use proper settings.
Wrong ignition timing - Set the ignition timing correctly.
Damaged thermostat - Replace thermostat.
Defective water pump - Change water pump as required.

Engine knocks or noises

Stale fuel - Change gasoline.
Engine is under excessive load - Load reducing required.
Low idle speed adjustment is incorrect - Correct the settings.
Fuel pump is dirty or defective - Clean or install new fuel pump.
Main bearings or crankshaft are worn out - Change or repair worn components.
Piston rings or cylinder bore are damaged - Replace faulty parts.

Engine power is too low

Clogged or incorrectly adjusted carburetor - Adjust carburetor properly or service it.
Fuel pump is faulty or clogged - Service or replace fuel pump.
Ignition failure - Test ignition and replace failed parts.
Damaged gaskets - Change gaskets.
Damaged powerhead parts - Defective components need to be replaced.

High fuel consumption

Incorrect adjustment of carburetor main jet - Adjust it correctly.
Spark plug is defective or loose - Re-tighten or change the spark plug.
Sleeve, piston, or rings are damaged - Replace defective components as required.

Trim motor runs but system does not move

Oil level low - Need to add the oil.
Pump assembly faulty - Inspect pump and change as required.
Manual shut-off valve leaks - Valve need to be closed or changed.
Motor or pump driveshaft faulty - Change defective component.

Trim does not fully up or down

Pump assembly is defective - Replace pump.
Tilt ram piston ball is not positioned correctly - Clean or repair.
Worn tilt ram piston O-ring - Change O-ring.
Lack of oil - Check oil level and add oil as required.
Lower check valve not seating in port side trim ram - Install valve correctly.