Mercury MERCRUISER Service Manual

Engine Will Not Start or Is Hard to Start
Possible Cause Remedy
Lanyard stop switch activated. Reset the lanyard stop switch.
Improper starting procedure. Read and follow the starting procedure.
Insufficient fuel supply. Fill the fuel tank or open valve.
Faulty ignition system component. Service the ignition system.
Clogged fuel filter. Replace the fuel filter.
Stale or contaminated fuel. Drain the fuel tank. Fill with fresh fuel.
Fuel line or tank vent line kinked or clogged. Replace kinked lines or blow out lines with compressed air to remove obstruction.
Faulty wire connections. Check wire connections.
MPI system fault.
Check the fuel system. Refer to MerCruiser ECM Fault Information and
Troubleshooting.
Engine Runs Rough, Misses, or Backfires
Possible Cause
Remedy
Clogged fuel filter. Replace the fuel filter.
Stale or contaminated fuel. Drain the fuel tank. Fill with fresh fuel.
Fuel line or tank vent line kinked or clogged. Replace kinked lines or blow out lines with compressed air to remove obstruction.
Flame arrestor dirty. Clean the flame arrestor.
Faulty ignition system component. Service the ignition system.
Idle speed too low.
Check the fuel system. Refer to Section 5.
MPI system fault.
Check the fuel system. Refer to MerCruiser ECM Fault Information and
Troubleshooting.
Poor Performance
Possible Cause
Remedy
Throttle not fully open. Inspect the throttle body for proper operation.
Damaged or improper propeller. Replace the propeller.
Excessive bilge water. Drain and check for cause of entry.
Boat overloaded or load improperly distributed. Reduce load or redistribute load more evenly.
Flame arrestor dirty. Clean the flame arrestor.
Boat bottom fouled or damaged. Clean or repair as necessary.
Ignition problem.
Refer to Engine Runs Rough, Misses, or Backfires.
Engine overheating.
Refer to Engine Overheat.
MPI system fault.
Check the fuel system. Refer to MerCruiser ECM Fault Information and
Troubleshooting.
Engine Overheat
Possible Cause
Remedy
Water inlet or seacock closed. Open the inlet or seacock.
Drive belt loose or in poor condition. Replace or adjust belt.
Seawater pickups or sea strainer obstructed. Remove obstruction.
Faulty thermostat. Replace the thermostat.
Coolant level (if equipped) low in the closed‑cooling section.
Check for cause of low coolant level and repair. Fill system with
proper coolant solution.
Heat exchanger or fluid cooler plugged with foreign material.
Clean heat exchanger, engine oil cooler, and transmission oil
cooler (if equipped).
Loss of pressure in the closed‑cooling section. Check for leaks. Clean, inspect, and test the pressure cap.
Faulty seawater pickup pump. Repair.
Engine Troubleshooting
Page 3C-10 © 2016 Mercury Marine 90-8M0099748 eng DECEMBER 2015

Mercury MERCRUISER Specifications

General

Brand	Mercury
Model	MERCRUISER
Category	Engine
Language	English