Diagnosing Electronically Controlled Fuel System Problems
Your Mercury Diesel authorized repair facility has the proper service tools for diagnosing problems on electronically controlled
fuel systems. The engine control module on these engines has the ability to detect some problems with the system when they
occur, and store a trouble code in the control module's memory. This code can then be read later by a service technician using
a special diagnostic tool.
Troubleshooting Charts
Starter Motor Will Not Crank Engine, or Cranks Slow
Possible Cause Remedy
Battery switch turned off. Turn switch on.
Remote control not in neutral position. Position control lever in neutral.
Open circuit breaker or blown fuse. Check and reset circuit breaker or replace fuse.
Loose or dirty electrical connections or damaged wiring.
Check all electrical connections and wires (especially battery
cables). Clean and tighten faulty connection.
Bad battery. Test and replace if bad.
Engine Will Not Start, or Is Hard to Start
Possible Cause
Remedy
Lanyard stop switch activated. Check lanyard stop switch.
Improper starting procedure. Read starting procedure.
Empty fuel tank or fuel shut off valve closed. Fill tank or open valve.
Faulty mechanical fuel delivery pump.
Have pump replaced by a Mercury Diesel–authorized repair facility if
fuel is present.
Throttle not operating properly. Check the throttle for freedom of movement.
Faulty electrical stop‑circuit.
Have a Mercury Diesel–authorized repair facility service the electrical
stop circuit.
Clogged fuel filters. Replace the filters.
Stale or contaminated fuel. Drain tank. Fill with fresh fuel.
Fuel line or tank vent line kinked or clogged.
Replace kinked lines or blow out the lines with compressed air to
remove obstruction.
Air in fuel injection system. Purge fuel injection system.
Faulty wire connections. Check wire connections.
Glow plugs or glow plug system inoperative, if
equipped.
Have a Mercury Diesel–authorized repair facility service the glow plug
system.
Electronic fuel system fault.
Have the electronic fuel system checked by a Mercury Diesel–
authorized repair facility.
Engine Runs Rough, Misses, or Backfires
Possible Cause
Remedy
Throttle not operating properly. Check the throttle for binding or an obstruction.
Idle speed too low. Check idle speed and adjust, if necessary.
Clogged fuel or air filters. Replace the filters.
Stale or contaminated fuel. Drain tank and fill with fresh fuel.
Kinked or clogged fuel line or fuel tank vent line.
Replace kinked lines or blow out lines with compressed air to remove
obstruction.
Air in fuel system. Purge fuel injection system.
Electronic fuel system faulty.
Have electronic system checked by a Mercury Diesel–authorized repair
facility.
Section 6 - Troubleshooting
Page 94 90-8M0145546 eng MAY 2018
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