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| Home / Outboard Engines / Mercury Engines / Mercury 15 MLH |
Mercury 15 MLH Troubleshooting
| Engine is not starting or hard starting |
Fuel tank is empty - Add fuel.
Low-quality gasoline - Change gasoline.
Air or water in fuel system - Remove water or air from fuel system.
Defective spark plug wire connection - Check spark plug wiring connection, repair or change.
Spark plug is defective - Spark plug need to be replaced.
Fuel filter is dirty - Replace fuel filter.
Fuel lines are dirty - Fuel lines must be clean.
Discharged or faulty battery - Battery needs to be recharged or replaced.
Bad harness connections - Inspect harness connections.
Ignition system failure - Check ignition system components and change if necessary.
Pulse fuel pump is faulty - Install new pulse fuel pump.
Electric fuel pump is faulty - Install new electric fuel pump.
ECM failure - Replace ECM.
| Engine starts and then stalls |
Damaged spark plug - Install new spark plug.
Ignition coil is damaged - Ignition coil should be replaced.
Damaged pulse fuel pump - Replace pulse fuel pump.
Fuel system is dirty - Fuel system need to be cleaned.
Final fuel filter is dirty - Replace or clean final filter.
Defective electric fuel pump - Electric fuel pump need to be replaced.
| Engine runs roughly |
Ignition system problems - Inspect ignition system and change failed components.
Fuel pump is faulty or clogged - Inspect fuel pump and change as required.
Restricted fuel lines - Service fuel lines.
Plugged fuel filter - Replace fuel filter.
| Engine overheats |
Engine is overloaded - Load reducing required.
Bad ignition timing - Ignition timing needs to be set properly.
Defective thermostat - Replace thermostat.
Water pump is defective - Replace water pump.
| Engine noise or knocking |
Stale gasoline - Use correct fuel.
Engine overloaded - Reduce load.
Incorrectly set low idle speed - Test and adjust.
Fuel pump is damaged or dirty - Service or change fuel pump.
Crankshaft or main bearings are worn out - Crankshaft or bearings need to be replaced.
Piston rings or cylinder bore are damaged - Change faulty parts.
| Engine power loss |
Fuel pump is dirty or defective - Inspect fuel pump and change as required.
Ignition system malfunction - Inspect ignition system and change faulty parts.
Damaged powerhead parts - Replace defective components as required.
Stator, coil, or switch box defective - Change faulty components.
Low compression - Correct.
Fuel supply problem - Check and repair.
Manifold fuel leak - Repair leaks.
Vapor separator is flooded - Check and correct malfunction.
| Engine using too much gasoline |
Loose or defective spark plug - Tighten or replace spark plug.
Sleeve, piston, or rings are damaged - Replace defective components as required.
Engine is running overloaded - Load reducing is recommended.
Fuel injectors are faulty or clogged - Service or replace fuel injectors.
| Trim motor is running but system can't move |
Oil insufficient - Checking oil level and add if necessary.
Pump assembly faulty - Inspect pump and change as required.
Leakage of manual release valve - Close the valve or change it.
Broken motor or pump driveshaft - Change defective component.
| Trim cannot be fully up or down |
Damaged pump assembly - Replace pump.
Tilt ram piston ball is displaced - Service or repair.
Worn tilt ram piston O-ring - Change O-ring.
Oil level low - Checking oil level and add if necessary.
Lower check valve is not properly secured in port side trim ram - Secure valve properly.
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| Engines Technical Specifications |