Engine Runs Rough, Misses And/Or Backfires; Poor Performance; Excessive Engine Temperature; November - MerCruiser Sterndrive 4.3 MPI User Manual

EFI system fault.

Engine Runs Rough, Misses And/Or Backfires

Clogged fuel filter.
Stale or contaminated fuel.
Kinked or clogged fuel line or fuel tank vent line.
Flame Arrestor dirty.
Faulty ignition system component.
Idle speed too low.
EFI System fault.

Poor Performance

Throttle not fully open.
Damaged or improper propeller.
Excessive bilge water.
Boat overloaded or load improperly distributed. Reduce load or redistribute load more evenly.
Flame arrestor dirty.
Boat bottom fouled or damaged.
Ignition problem.
Engine overheating.
EFI System fault

Excessive Engine Temperature

Water inlet or seacock closed.
Drive belt loose or in poor condition.
Seawater pickups or sea strainer obstructed.
Faulty thermostat.
Coolant level (if equipped) low in closed cooling
section.
Heat Exchanger or Fluid Cooler plugged with foreign
material
Loss of pressure in closed cooling section.
Faulty seawater pickup pump.
Seawater discharge restricted or plugged.

90-864195061 NOVEMBER 2006

Possible Cause
Possible Cause
Possible Cause
Possible Cause
Remedy
Have EFI System checked by an authorized Mercury
MerCruiser dealer.
Replace filter.
If contaminated, drain tank. Fill with fresh fuel.
Replace kinked lines or blow out lines with compressed air
to remove obstruction.
Clean Flame Arrestor.
Service ignition system.
Have EFI system checked by an authorized Mercury
MerCruiser dealer.
Have EFI System checked by an authorized Mercury
MerCruiser dealer.
Inspect the throttle cable and linkages for proper operation.
Replace the propeller.
Drain and check for cause of entry.
Clean the flame arrestor.
Clean or repair as necessary.
See Engine Runs Rough, Misses or Backfires.
See Excessive Engine Temperature.
Have EFI System checked by an authorized Mercury
MerCruiser dealer.
Open.
Replace or adjust belt.
Remove obstruction.
Replace.
Check for cause of low coolant level and repair. Fill
system with proper coolant solution.
Clean Heat Exchanger, Engine Oil Cooler, and
Transmission Oil Cooler (if equipped).
Check for leaks. Clean, inspect and test pressure cap.
Repair.
Clean exhaust elbows.
Section 7 - Troubleshooting
Remedy
Remedy
Remedy
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