Cummins/Onan 4000 troubleshooting: 8 fault codes and symptom-cause-remedy entries from the manufacturer's own service documentation.
Cummins/Onan 4000 — full specs, parts & maintenance.
All Cummins/Onan fault codes →
| Symptom | Remedy |
|---|---|
| The engine fails to crank. | A. Try starting at the genset rather than at the remote control. b. Replace fuse F1 on the control panel if it has blown. c. Clean and tighten the positive (+) and negative (-) battery cable connections at the battery and the genset. d. Recharge the battery. Refer to the battery manufacturer's recommendations. |
| The engine cranks slowly. | A. Disconnect the air conditioner and other large loads. b. Clean and tighten the positive (+) and negative (-) battery cable connections at the battery and the genset. c. Recharge the battery. Refer to the battery manufacturer's recommendations. d. Change the engine oil to oil having the proper viscosity for the ambient temperature. See Table 1. |
| The engine cranks but fails to start. | A. Check the fuel tank and fill if necessary. b. Open any closed fuel shut off valve. c. Check engine oil level and add oil as necessary. d. Replace fuse F2 (side of control panel) if it has blown. e. Service the air cleaner. f. Secure the spark plug leads on the spark plugs. g. Replace the spark plugs. |
| The engine runs and then stops or surges. | A. Check the fuel tank and fill if necessary. b. Check the engine oil level and add oil as necessary. Drain excess oil if the level is above the dipstick Full mark. c. Check and reset the carburetor preheater lever and altitude adjust knob. See Varying Weather and Altitude. d. Secure the spark plug leads on the spark plugs. e. Replace the spark plugs. |
| There is no electrical power even though the genset runs. | A. Reset tripped circuit breakers. See Powering Equipment. b. Unless there is an automatic power transfer switch, plug the boat power cord into the genset power output receptacle (if so equipped) or turn the pontoon boat power selector switch to its genset position (if so equipped). |
| The remote battery condition meter indicates low voltage. | A. Clean and tighten the positive (+) and negative (-) battery cable connections at the battery and the genset. b. Recharge the battery. Refer to the battery manufacturer's recommendations. |
| The genset keeps stalling or the circuit breaker keeps tripping. | Try running with fewer appliances connected. See Powering Equipment. |
| Black smoke exits the tailpipe. | Service the air cleaner. |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.