MerCruiser 350 MAG MPI User Manual

Section 7 - Troubleshooting
90-864195070 JUNE 2007 Page 135
Possible Cause Remedy
EFI system fault.
Have EFI System checked by an authorized Mercury
MerCruiser dealer.
Engine Runs Rough, Misses And/Or Backfires
Possible Cause Remedy
Clogged fuel filter. Replace filter.
Stale or contaminated fuel. If contaminated, drain 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 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.

MerCruiser 350 MAG MPI Specifications

General

Engine Type	V8
Horsepower	300 HP
Ignition System	Electronic ignition
Alternator	65 amp
Compression Ratio	9.4:1
Displacement	5.7L (350 cu in)
Fuel System	Multi-Point Injection (MPI)
Bore x Stroke	4.00" x 3.48" (101.6mm x 88.39mm)