Mercury 400 L6 Verado Problems
| Engine Model: Mercury Verado 400 L6 |
| Engine Type: 4-stroke 6-cylinder DOHC 24-valve supercharged gasoline outboard engine |
| Total Displacement: 158.5 cu.in (2.6 L) |
| Rated Engine Power: 400 Hp (298 kW) at 6800 rpm |
| Fuel System: Sequential multi-point electronic fuel injection (EFI) |
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| Engine starts hard or won't start |
No fuel in fuel tank - Fill gasoline up.
Wrong grade of gasoline - Use correct fuel grade.
Clogged fuel system - Remove clogging.
Disconnected or loose spark plug wire - Inspect the spark plug wire connection, replace or repair.
Spark plug is defective - Change spark plug as required.
Fuel filter is dirty - Install new filter.
Damaged or wear vapor separator needle valve - Change vapor separator needle valve.
Dirty fuel lines - Service fuel lines.
Fuel tank air vent clogged or closed - Open or clean air vent.
Fuel feed pump failure - Install new feed pump or repair it.
Choke cable is damaged or not adjusted properly - Replace cable or adjust correctly.
Incorrect valve clearance - Need to adjust valve clearance.
Valve timing is wrong - Set the valve timing correctly.
Low fuel pressure - Inspect fuel system for leaks or inspect low pressure fuel pump.
Fuel injector is damaged or dirty - Replace or clean if necessary.
Fuel regulator is faulty - Replace fuel regulator.
Electronic control modul failure - Replace ECM.
| Engine starts but stalls immediately |
Damaged spark plug - Change spark plug as required.
Worn or defective vapor separator needle valve - Change vapor separator needle valve.
Defective ignition coil - Change ignition coil as required.
Closed or restricted fuel tank air vent - Open or service air vent.
Defective fuel pump - Replace or rebuild fuel pump.
Damaged choke system - Change choke system components as required.
Excessive valve clearance - Check and adjust.
Wrong valve timing - Adjust valve timing as required.
Worn or loose valve springs - Replace valve springs.
Valves sticking - Valves must be cleaned.
Poor compression - Check and change damaged parts.
Fuel filter is clogged - Install new filter.
Fuel injector is clogged or malfunction - Clean or replace if necessary.
Lack of engine oil - Fill the crankcase with engine oil.
Oil pump failure - Change oil pump as required.
Water intake is blocked - Wash or clean as required.
Faulty thermostat - Thermostat need to be replaced.
Water pump malfunction - Install new water pump.
Ignition system malfunction - Inspect ignition system and change failed components.
Fuel pump is dirty or defective - Test fuel pump and replace if necessary.
Vapor separator needle valve is bend or wear - Replace needle valve.
Dirt in the fuel lines - Clean fuel system lines.
Fuel tank air vent restricted or closed - Open or clean air vent.
Fuel filter is clogged - Replace fuel filter.
Intake manifold air leaks - Install new gasket.
Water intake is clogged - Need to clean or wash.
Throttle link and throttle valve are worn or damaged - Replace faulty parts.
Damaged or clogged fuel injector - Clean or replace if necessary.
Engine is running overloaded - Load reducing is recommended.
Fuel injector or fuel pump is clogged - Replace or clean as required.
Bad ignition timing - Set the ignition timing correctly.
Thermostat is defective - Install new thermostat.
Water pump is defective - Change water pump.
Incorrect propeller selection - Install correct propeller.
Damaged or improper size of propeller - Have propeller repaired or replaced.
Outboard engine is positioned too low or too high - Mount the motor as required.
Engine oil insufficient - Fill the crankcase with engine oil.
Oil pump malfunction - Replace oil pump.
Water intake is clogged - Wash or clean as required.
Incorrect valve setting - Set the valves correctly.
Low octane fuel - Use proper fuel.
Engine is overloaded - Reduce load.
Low idle speed adjustment is incorrect - Adjustment required.
Fuel pump is damaged or dirty - Test fuel pump and change if necessary.
Crankshaft or main bearings failure - Crankshaft or bearings need to be replaced.
Damaged piston rings or cylinder bore - Change faulty parts.
Fuel lines are dirty - Fuel lines need to be cleaned.
Fuel injector is fault - Inspect fuel injector and change as required.
Fuel pump is clogged or faulty - Test fuel pump and replace if necessary.
Ignition system problems - Check ignition and replace faulty components.
Cylinder head gasket is blown - Install new head gasket.
Powerhead parts are worn out - Replace defective components.
Stuck or burned valves - Replace or clean valves.
Propeller selection improperly - Check the propeller size.
Damaged or improper size of propeller - Have propeller repaired or replaced.
Incorrect outboard motor mounting height - Adjust the engine to correct transom height.
Improper trim angle - Make the correct trim angle adjustment.
| Engine uses too much fuel |
Damaged or clogged fuel injector - Clean or replace if necessary.
Faulty or loose spark plug - Re-tighten or replace spark plug.
Worn rings, piston, or sleeve - Replace defective components as required.
ECU is not functioning - Change electronic control unit.
| Excessive engine vibration |
Propeller bent or damaged - Replace propeller.
Propeller shaft damaged - Replace propeller shaft.
Weeds wraped around propeller - Clean the propeller.
Engine mounting bolt is not tightened - Tighten bolt.
Loose or faulty steering pivot Tighten correctly or replace.
Battery voltage is low - Recharge the battery.
Battery does not hold charge - Service or change the battery.
Disconnected cables or faulty battery terminals - Connect wiring correctly or install new terminals.
Starter motor is damaged - Change or repair starter.
| Trim motor runs but trim system does not move up or down |
Lack of oil - Need to add the oil.
Damaged pump assembly - Test pump and replace if necessary.
Leakage of manual drain valve - Close the valve or change it.
Motor or pump driveshaft faulty - Replace defective component.
| Trim does not fully up or down |
Pump assembly is damaged - Replace pump.
Tilt ram piston ball is not positioned correctly - Clean or repair.
Worn tilt ram piston O-ring - Replace O-ring.
Oil level is low - Check and refill oil.
Lower check valve not seating in port side trim ram - Secure valve properly.
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