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| Home / Outboard Engines / Mercury Engines / Mercury 40 Bigfoot |
Mercury 40 Bigfoot Troubleshooting
| Engine hard to start or will not start |
Empty fuel tank - Fill fuel up.
Improper fuel grade - Change gasoline.
Fuel system clogged - Repair or replace.
Spark plug wire is disconnected or loose - Inspect the spark plug wire connection, replace or repair.
Spark plug is defective - Change spark plug as required.
Fuel filter is dirty - Change fuel filter.
Fuel lines clogging - Clean fuel system lines.
Discharged or worn battery - Battery needs to be recharged or replaced.
Damaged wiring harness connections - Inspect harness connections.
Defective ignition system - Check ignition system components and change if necessary.
Defective pulse fuel pump - Change pulse fuel pump.
Electric fuel pump is faulty - Change electric fuel pump.
Electronic control modul failure - Change electronic control modul.
| Engine starts and stops suddenly |
Spark plug is damaged - Spark plug need to be replaced.
Ignition coil is not working - Change ignition coil as required.
Pulse fuel pump is faulty - Pulse fuel pump need to be replaced.
Fuel system is clogged - Clean fuel system.
Plugged final fuel filter - Install new final filter.
Electric fuel pump is faulty - Change electric fuel pump.
| Engine runs irregularly |
Defective ignition system - Check ignition and replace faulty components.
Fuel pump is faulty or clogged - Inspect fuel pump and change as required.
Fuel lines are dirty - Clean fuel system lines.
Plugged fuel filter - Change fuel filter.
| Engine keeps overheating |
Engine overloaded - Load reducing required.
Improper ignition timing - Set the ignition timing properly.
Defective thermostat - Replace thermostat.
Damaged water pump - Water pump need to be replaced.
| Abnormal engine knocking or noise |
Stale fuel - Change gasoline.
Excessive engine load - Reduce load.
Wrong adjustment of low idle speed - Adjust idle speed.
Fuel pump is damaged or dirty - Test fuel pump and change if necessary.
Main bearings or crankshaft wear - Replace crankshaft or bearings.
Piston rings or cylinder bore are worn - Replace defective parts.
| Engine power is insufficient |
Dirty or faulty fuel pump - Service or change fuel pump.
Defective ignition - Check ignition and replace faulty components.
Powerhead parts are worn out - Replace defective parts.
Failed switch box, stator, or coil - Change damaged parts.
Compression is insufficient - Correct.
Fuel delivery problem - Check and repair.
Manifold fuel leak - Leak must be repaired.
Vapor separator is flooded - Normalize vapor separator functions.
| High fuel consumption |
Spark plug is defective or loose - Spark plug need to be replaced or tightened.
Worn rings, piston, or sleeve - Replace faulty parts as required.
Engine is running overloaded - Load reducing is recommended.
Fuel injectors are clogged or faulty - Check fuel injectors and change if required.
| Trim motor is running but system can't move |
Low oil level - Check oil level and add oil as required.
Pump assembly is defective - Inspect pump and change as required.
Manual shut-off valve leaks - Close the valve fully or replace it.
Motor or pump driveshaft faulty - Change worn component.
| Trim does not fully up or down |
Pump assembly faulty - Replace pump.
Tilt ram piston ball is displaced - Service or repair.
Damaged tilt ram piston O-ring - Replace O-ring.
Low oil level - Fill up oil to required level.
Lower check valve not seating in port side trim ram - Secure valve properly.
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| Engines Technical Specifications |