________________________________________________________________________________________
| Home / Outboard Engines / Mercury Engines / Mercury 20 EFI |
Mercury 20 EFI Troubleshooting
| Engine difficult to start or will not start |
Empty fuel tank - Fill it up.
Low-quality gasoline - Use quality fuel.
Air trapped in fuel system - Bleed air.
Spark plug wire connection are damaged - Inspect the spark plug wire connection, replace or repair.
Defective spark plug - Spark plug need to be replaced.
Fuel filter is plugged - Fuel filter needs changing.
Dirt in the fuel lines - Clean fuel system lines.
Discharged or defective battery - Battery needs to be recharged or replaced.
Wiring harness connections are damaged - Inspect harness connections.
Ignition system malfunction - Change defective parts.
Faulty pulse fuel pump - Change pulse fuel pump.
Electric fuel pump is faulty - Electric fuel pump need to be replaced.
Electronic control modul failure - Replace ECM.
| Engine starts and stops |
Defective spark plug - Install new spark plug.
Ignition coil is not working - Install a new ignition coil.
Pulse fuel pump is defective - Install new pulse fuel pump.
Fuel system is dirty - Service fuel system.
Final fuel filter is plugged - Install new final filter.
Electric fuel pump failure - Change electric fuel pump as required.
| Engine runs roughly |
Defective ignition - Check ignition system and replace faulty parts.
Fuel pump is damaged or dirty - Service or change fuel pump.
Clogged fuel lines - Service fuel lines.
Plugged fuel filter - Fuel filter needs changing.
| Engine overheated |
Engine overloaded - Reduce load.
Bad ignition timing - Set the ignition timing correctly.
Damaged thermostat - Thermostat need to be replaced.
Water pump malfunction - Water pump need to be replaced.
| Abnormal engine knocking or noise |
Stale fuel - Use correct gasoline.
Engine overloaded - Reduce load.
Incorrectly set low idle speed - Correct idle settings.
Fuel pump is defective or dirty - Service or replace fuel pump.
Crankshaft or main bearings failure - Change or repair worn components.
Piston rings or cylinder bore are damaged - Replace defective components.
| Engine loses power |
Fuel pump is clogged or faulty - Check fuel pump and change if required.
Ignition system problems - Test ignition and replace failed parts.
Powerhead parts are damaged - Replace defective components.
Stator, coil, or switch box defective - Change damaged parts.
Bad compression - Normalize compression.
Fuel delivery problem - Check fuel system.
Manifold is leaking - Repair leaks.
Vapor separator is flooded - Check and correct malfunction.
| Engine uses too much fuel |
Spark plug is defective or loose - Tighten or replace spark plug.
Worn sleeve, piston, or rings - Replace defective components as required.
Engine overloaded - Load reducing is recommended.
Fuel injectors are damaged or dirty - Service or replace fuel injectors.
| Trim motor runs but system does not move |
Oil level is insufficient - Check oil level and add oil as required.
Pump assembly faulty - Inspect pump and change as required.
Manual release valve leaking - Valve need to be closed or changed.
Faulty pump driveshaft or motor - Change defective component.
| Trim does not fully up or down |
Damaged pump assembly - Replace pump.
Tilt ram piston ball is in wrong position - Clean or repair.
Damaged tilt ram piston O-ring - Replace O-ring.
Insufficient oil - Check oil level and add oil as required.
Lower check valve not seating in port side trim ram - Secure valve properly.
________________________________________________________________________________________
________________________________________________________________________________________
| Engines Technical Specifications |