Section 7 - Troubleshooting
90-8M0099741
eng
JUNE 2015
Page 79
Engine Runs Rough, Misses, or Backfires
Possible Cause
Remedy
Clogged fuel filter.
Replace filter.
Stale or contaminated fuel.
Drain fuel tank. 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.
Flame arrestor dirty.
Clean the flame arrestor.
Faulty ignition system component.
Service ignition system.
Idle speed too low.
Have EFI system checked by an authorized Mercury MerCruiser dealer.
EFI system fault.
Have EFI system checked by an authorized Mercury MerCruiser dealer.
Poor Performance
Possible Cause
Remedy
Throttle not fully open.
Inspect the throttle cable and linkages 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.
See
Engine Runs Rough, Misses, or Backfires
.
Engine overheating.
See
Excessive Engine Temperature
.
EFI system fault.
Have EFI system checked by an authorized Mercury MerCruiser dealer.
Excessive Engine Temperature
Possible Cause
Remedy
Water inlet or seacock closed.
Open.
Drive belt loose or in poor condition.
Replace or adjust belt.
Seawater pickups or sea strainer obstructed.
Remove obstruction.
Faulty thermostat.
Replace.
Coolant level (if equipped) low in 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 closed cooling section.
Check for leaks. Clean, inspect, and test pressure cap.
Faulty seawater pickup pump.
Repair.
Seawater discharge restricted or plugged.
Clean exhaust elbows.
Insufficient Engine Temperature
Possible Cause
Remedy
Faulty thermostat.
Replace.
