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| Home / Outboard Engines / Mercury Engines / Mercury 15 MH |
Mercury 15 MH Troubleshooting
| Engine hard to start or doesn't start |
No gasoline in tank - Add fuel.
Wrong grade of gasoline - Use quality gasoline.
Air in the fuel pipes - Bleed the fuel pipes.
Disconnected or loose spark plug wire - Inspect spark plug wiring connection, change or repair.
Faulty spark plug - Install new spark plug.
Dirty fuel filter - Replace fuel filter.
Clogged fuel lines - Clean fuel system lines.
Drained or worn battery - Charge or replace the battery.
Damaged wiring harness connections - Check electrical wire harness connections.
Ignition system malfunction - Check ignition components and replace if necessary.
Faulty pulse fuel pump - Replace pulse fuel pump.
Defective electric fuel pump - Install new electric fuel pump.
Electronic control modul failure - Install new ECM.
| Engine starts but then stalls |
Spark plug is defective - Spark plug need to be replaced.
Ignition coil is faulty - Ignition coil should be replaced.
Defective pulse fuel pump - Install new pulse fuel pump.
Fuel system is clogged - Fuel system need to be cleaned.
Final fuel filter is plugged - Install new final filter.
Electric fuel pump is faulty - Install new electric fuel pump.
| Irregular engine running |
Ignition system failure - Test ignition and replace failed parts.
Fuel pump is faulty or clogged - Check fuel pump and change if required.
Clogged fuel lines - Fuel lines need to be cleaned.
Fuel filter is clogged - Change fuel filter.
| Engine overheating |
Excessive engine load - Reduce engine load.
Bad ignition timing - Set the ignition timing properly.
Damaged thermostat - Change thermostat as required.
Damaged water pump - Change water pump.
| Engine knocking or noise |
Low octane gasoline - Use correct fuel.
Engine is overloaded - Reduce load.
Low idle speed setting is not correct - Test and adjust.
Clogged or defective fuel pump - Inspect fuel pump and change as required.
Crankshaft or main bearings failure - Worn parts replacement required.
Piston rings or cylinder bore are worn - Change defective components.
| Engine lacks power |
Dirty or faulty fuel pump - Clean or install new fuel pump.
Ignition failure - Check ignition and replace faulty components.
Powerhead components are worn - Change defective components.
Stator, coil, or switch box defective - Change damaged parts.
Bad compression - Correct.
Fuel delivery problem - Check fuel system.
Manifold is leaking - Repair leaks.
Vapor separator is flooded - Normalize vapor separator functions.
| High fuel consumption |
Spark plug is loose or defective - Re-tighten or change the spark plug.
Worn sleeve, piston, or rings - Replace defective components as required.
Engine is overloaded - Reduce load.
Dirty or defective fuel injectors - Clean or replace fuel injectors.
| Trim motor runs but system does not move |
Not enough oil - Fill up oil to required level.
Damaged pump assembly - Check pump and replace if necessary.
Leakage of manual drain valve - Close the valve or change it.
Broken motor or pump driveshaft - Change defective component.
| Trim cannot be fully up or down |
Pump assembly faulty - Change pump.
Tilt ram piston ball is not positioned correctly - Clean or repair.
Tilt ram piston O-ring damaged - Install new O-ring.
Insufficient oil - Check oil level and add oil as required.
Lower check valve is not properly secured in port side trim ram - Install valve correctly.
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| Engines Technical Specifications |