Cummins/Onan Marquis Gold Engine

How to read your Cummins/Onan engine serial & model number →

• UNIT STARTS AND RUNS, THEN STOPS WHEN THE START SWITCH IS RELEASED
  Cause: 1. Low fluid levels.
  Fix: Check & bring all fluids up to the appropriate levels.
• UNIT RUNS THEN SURGES
  Cause: 1. Loose or worn spark plug leads. 2. Defective ignition coil, wiring, or control components. 3. Faulty spark plug. 4. Governor out of adjustment. 5. Combustion air pre-heat malfunction. 6. Carburetor icing. 7. Carburetor varnishing.
  Fix: 1. Check spark plug leads at spark plug & ignition coil. 2. Contact an Onan Authorized RV Service & Parts Dealer. 3. Remove spark plug & clean or replace. 4. Contact an Onan Authorized RV Service & Parts Dealer. 5. Contact an Onan Authorized RV Service & Parts Dealer. 6. Move carburetor pre-heater to the winter position. 7. Try fuel system cleaner and contact dealer if no change.
• UNIT RUNS THEN STOPS, OR STOPS WHEN DRIVING AROUND A CORNER
  Cause: 1. Low fuel level. 2. Low oil level. 3. Excess oil.
  Fix: 1. Add fuel. 2. Add oil. 3. Reduce engine oil level.
• FAILS TO CRANK
  Cause: 1. Low battery. 2. Bad battery connection. 3. Blown fuse.
  Fix: 1. Check battery fluid level. 2. Clean & tighten all battery & cable connections. 3. Replace fuse on control panel.
• EXHAUSTING BLACK SMOKE
  Cause: 1. Dirty air filter.
  Fix: Replace air filter.
• CRANKS SLOWLY
  Cause: 1. Low battery. 2. Bad battery connection. 3. Incorrect oil viscosity. 4. Load connected.
  Fix: 1. Check battery fluid level. 2. Clean & tighten all battery & cable connections. 3. Replace with recommended viscosity oil. 4. Disconnect load before starting.
• CRANKS BUT WON’T START
  Cause: 1. Fuel below generator pickup level in tank. 2. Fuel supply shutoff valve closed. 3. Carbon deposits on spark plug(s). 4. Low oil level.
  Fix: 1. Add fuel. 2. Fully open fuel supply valve. 3. Remove spark plug(s) and replace. 4. Add oil.
• CIRCUIT BREAKER TRIPS
  Cause: 1. Overloaded circuit.
  Fix: Turn-off some of the electrical load, and reset the circuit breaker.

Compiled from service & troubleshooting documentation across every generator set that uses the Cummins/Onan Marquis Gold.

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