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| Home / Outboard Engines / Mercury Engines / Mariner 40 EFI |
Mariner 40 EFI Troubleshooting
| Engine will not start or starts up hard |
Empty gas tank - Fill gasoline up.
Incorrect fuel grade - Change gasoline.
Dirt and debris in fuel system - Remove debris and dirt.
Defective spark plug wire connection - Inspect the spark plug wire connection, replace or repair.
Defective spark plug - Change spark plug as required.
Fuel filter is dirty - Fuel filter needs changing.
Dirt in the fuel lines - Clean fuel system lines.
Discharged or faulty battery - Need to charge or replace the battery.
Bad harness connections - Inspect harness connections.
Damaged ignition system - Change defective parts.
Defective pulse fuel pump - Pulse fuel pump need to be replaced.
Damaged electric fuel pump - Install new electric fuel pump.
ECM failure - Install new ECM.
| Engine starts but then shuts off |
Faulty spark plug - Install new spark plug.
Damaged ignition coil - Replace ignition coil as necessary.
Damaged pulse fuel pump - Pulse fuel pump need to be replaced.
Fuel system is dirty - Fuel system need to be cleaned.
Final fuel filter is clogged - Replace fuel filter.
Defective electric fuel pump - Electric fuel pump need to be replaced.
| Irregular engine running |
Defective ignition - Test ignition and replace failed parts.
Fuel pump is dirty or defective - Clean or install new fuel pump.
Dirt in the fuel lines - Service fuel lines.
Plugged fuel filter - Install new filter.
| Engine is overheated |
Engine overload - Load reducing required.
Ignition timing is wrong - Set the ignition timing correctly.
Thermostat is defective - Change thermostat as required.
Water pump failure - Change water pump.
| Abnormal engine noise or knocking |
Stale fuel - Change fuel.
Engine is overloaded - Load reducing required.
Low idle speed setting is incorrect - Adjust as required.
Fuel pump is dirty or defective - Test fuel pump and change if necessary.
Worn crankshaft or main bearings - Worn parts replacement required.
Worn piston rings or cylinder bore - Replace faulty components.
| Engine lacks power |
Fuel pump is clogged or faulty - Test fuel pump and change if necessary.
Defective ignition system - Test ignition and replace failed parts.
Powerhead components are faulty - Replace defective parts.
Stator, coil, or switch box defective - Replace damaged components.
Bad compression - Normalize compression.
Fuel delivery problem - Check fuel system.
Manifold fuel leak - Repair leaks.
Vapor separator flooding over - Normalize vapor separator functions.
| Excessive fuel consumption |
Loose or defective spark plug - Tighten or replace spark plug.
Piston, sleeve, or rings are damaged - Replace defective components.
Excessive engine load - Reduce load.
Fuel injectors are clogged or faulty - Clean or change fuel injectors.
| Trim motor is running but system can't move |
Not enough oil - Check oil level and add oil as required.
Pump assembly is defective - Check pump and replace if necessary.
Manual shut-off valve leaks - Close the valve or change it.
Motor or pump driveshaft faulty - Replace worn component.
| Trim cannot be fully up or down |
Damaged pump assembly - 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 - Secure valve properly.
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