Cummins/Onan 6 - 3.25 inch (82.55 mm) x 2.875 inch (73 mm) Engine Engine

• VOLTAGE UNSTEADY BUT ENGINE NOT MISFIRING
  Cause: Speed too low. Injection pump fuel metering shaft not properly adjusted. Poor commutation or brush contact. Loose connections.
  Fix: Adjust governor to correct speed. Adjust as instructed under SPECIAL ADJUSTMENTS. Refinish commutator or undercut mica if necessary. See that brushes seat well on commutator and collector rings (where used), are free in holders, are not worn shorter than 5/8
• Vessel bilge must have an operating power exhaust
  Fix: Ensure the vessel bilge has a functioning power exhaust system.
• Vehicle exhaust system must extend beyond vehicle perimeter and not near windows, doors or venis
  Fix: Ensure the vehicle exhaust system extends beyond the vehicle perimeter and is not located near windows, doors, or venis.
• TOO SMALL LINE WIRE USED FOR LOAD AND DISTANCE
  Fix: Install larger or extra wires or reduce load.
• TOO MUCH FUEL BEING INJECTED
  Fix: Check condition and adjustment of governor, injection pump and nozzle. NOTE: stop unit at once and determine cause.
• TOO LARGE BEARING CLEARANCE
  Fix: Replace bearings necessary.
• The FAULT 1 or FAULT 2 fault lamp lights.
  Fix: Engine shuts down immediately, engine runs for several seconds and then shuts down, or engine continues to run. The standard undesignated fault functions are programmed to shut down the set when a fault is sensed. Fault 1 is timed delayed while Fault 2 is immediate. The nature of the fault is an optional selection that is determined when the set installation is designed. The undesignated fault functions may also be programmed for non-shutdown or non-time delay.
• TAPPING SOUND
  Cause: Valve clearance too great.
  Fix: Adjust
• SWITCH OFF lamp flashes.
  Fix: Indicates Run-Stop-Remote switch is in the Stop position which will prevent automatic Starting. Moving the Run-Stop-Remote switch to the Remote position will stop the lamp flashing and enable automatic starting.
• SHARP METALLIC THUD, ESPECIALLY WHEN COLD ENGINE FIRST STARTED
  Cause: Low oil supply. Oil badly diluted.
  Fix: Add oil. Change oil.
• POWER DROPS UNDER HEAVY LOAD
  Cause: Engine lacks power. Poor compression. Faulty carburetion. Restricted air cleaner. Faulty choke.
  Fix: See remedies for engine missing under heavy load. Tighten cylinder head and spark plug. If still not corrected, grind the valves, Replace piston rings, if necessary. Check the fuel system. Clean, adjust or replace parts necessary.
• POOR COMPRESSION
  Cause: Worn piston, rings, or cylinder.
  Fix: Refinish cylinder. Install oversize piston and rings.
• PINGING SOUND WHEN ENGINE IS RAPIDLY ACCELERATED OR HEAVILY LOADED
  Cause: Carbon in cylinder. Spark too early. Wrong spark plug. Spark plug burned or carboned.
  Fix: Remove carbon. Reset breaker points or retime magento. Install correct spark plug. Install new plug.
• OIL TOO LIGHT OR DILUTED
  Fix: Drain. Refill with proper oil.
• No AC output voltage.
  Fix: Voltage regulator is inoperative. Refer to Initial Start and Checks, and Adjustments sections of your Installation Manual for voltage check and adjustment procedures. Contact your distributor if voltage build-up is still a problem.

Compiled from service & troubleshooting documentation across every generator set that uses the Cummins/Onan 6 - 3.25 inch (82.55 mm) x 2.875 inch (73 mm).

Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.