Section 7 - Troubleshooting
90-899883179 OCTOBER 2007 Page 109
Possible Cause Remedy
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.
Running rich. Have authorized Mercury MerCruiser dealer check and repair.
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.
Low Engine Oil Pressure
Possible Cause Remedy
Insufficient oil in crankcase. Check and add oil.
Excessive oil in crankcase (causing it to become
aerated).
Check and remove required amount of oil. Check for
cause of excessive oil (improper filling).
Diluted or improper viscosity oil.
Change oil and oil filter, using correct grade and
viscosity oil. Determine cause for dilution (excessive
idling).
Battery Will Not Recharge
Possible Cause Remedy
Excessive current draw from battery. Turn off non‑essential accessories.
Alternator drive belt loose or in poor condition. Replace and/or adjust.
Unacceptable battery condition. Test battery, replace if necessary.
Loose or dirty electrical connections or damaged
wiring.
Check all associated electrical connections and wires
(especially battery cables). Clean and tighten faulty
connections. Repair or replace damaged wiring.
Faulty alternator Test alternator output, replace if necessary.
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