Cummins/Onan 4000 troubleshooting: 26 symptom-cause-remedy entries from the manufacturer's own service documentation.
Cummins/Onan 4000 — full specs, parts & maintenance.
All Cummins/Onan fault codes →
| Symptom | Cause | Remedy |
|---|---|---|
| The engine fails to crank. | Try starting at the genset rather than at the remote control. | |
| The engine fails to crank. | Fuse F1 on the control panel has blown. | Replace fuse F1 on the control panel if it has blown. |
| The engine fails to crank. | Loose or dirty positive (+) and negative (-) battery cable connections at the battery and the genset. | Clean and tighten the positive (+) and negative (-) battery cable connections at the battery and the genset. |
| The engine fails to crank. | Battery discharged. | Recharge the battery. Refer to the battery manufacturer's recommendations. |
| The engine cranks slowly. | Air conditioner and other large loads connected. | Disconnect the air conditioner and other large loads. |
| The engine cranks slowly. | Loose or dirty positive (+) and negative (-) battery cable connections at the battery and the genset. | Clean and tighten the positive (+) and negative (-) battery cable connections at the battery and the genset. |
| The engine cranks slowly. | Battery discharged. | Recharge the battery. Refer to the battery manufacturer's recommendations. |
| The engine cranks slowly. | Engine oil viscosity not proper for the ambient temperature. | Change the engine oil to oil having the proper viscosity for the ambient temperature. See Table 1. |
| The engine cranks but fails to start. | Fuel tank empty. | Check the fuel tank and fill if necessary. |
| The engine cranks but fails to start. | Closed fuel shut off valve. | Open any closed fuel shut off valve. |
| The engine cranks but fails to start. | Low engine oil level. | Check engine oil level and add oil as necessary. |
| The engine cranks but fails to start. | Fuse F2 (side of control panel) has blown. | Replace fuse F2 (side of control panel) if it has blown. |
| The engine cranks but fails to start. | Air cleaner dirty. | Service the air cleaner. |
| The engine cranks but fails to start. | Spark plug leads loose on the spark plugs. | Secure the spark plug leads on the spark plugs. |
| The engine cranks but fails to start. | Spark plugs worn or fouled. | Replace the spark plugs. |
| The engine runs and then stops or surges. | Fuel tank empty. | Check the fuel tank and fill if necessary. |
| The engine runs and then stops or surges. | Engine oil level incorrect (low or above the dipstick Full mark). | Check the engine oil level and add oil as necessary. Drain excess oil if the level is above the dipstick Full mark. |
| The engine runs and then stops or surges. | Carburetor preheater lever and altitude adjust knob not set correctly. | Check and reset the carburetor preheater lever and altitude adjust knob. See Varying Weather and Altitude. |
| The engine runs and then stops or surges. | Spark plug leads loose on the spark plugs. | Secure the spark plug leads on the spark plugs. |
| The engine runs and then stops or surges. | Spark plugs worn or fouled. | Replace the spark plugs. |
| There is no electrical power even though the genset runs. | Tripped circuit breakers. | Reset tripped circuit breakers. See Powering Equipment. |
| There is no electrical power even though the genset runs. | Boat power cord not plugged into the genset power output receptacle or power selector switch not in its genset position (unless there is an automatic power transfer switch). | 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 (Fig. 4) indicates low voltage. | Loose or dirty positive (+) and negative (-) battery cable connections at the battery and the genset. | Clean and tighten the positive (+) and negative (-) battery cable connections at the battery and the genset. |
| The remote battery condition meter (Fig. 4) indicates low voltage. | Battery discharged. | Recharge the battery. Refer to the battery manufacturer's recommendations. |
| The genset keeps stalling or the circuit breaker keeps tripping. | Too many appliances connected. | Try running with fewer appliances connected. See Powering Equipment. |
| Black smoke exits the tailpipe. | Air cleaner dirty. | 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.
Documented causes: Fuel tank empty.; Closed fuel shut off valve.; Low engine oil level.; Fuse F2 (side of control panel) has blown.. See the table for the matching fixes.
Documented causes: Fuel tank empty.; Engine oil level incorrect (low or above the dipstick Full mark).; Carburetor preheater lever and altitude adjust knob not set correctly.; Spark plug leads loose on the spark plugs.. See the table for the matching fixes.
Documented causes: Air conditioner and other large loads connected.; Loose or dirty positive (+) and negative (-) battery cable connections at the battery and the genset.; Battery discharged.; Engine oil viscosity not proper for the ambient temperature.. See the table for the matching fixes.