Separate the diesel engine from the electrical generator.
| Symptom | First branch |
|---|---|
| Starter does not turn | DC battery, cables, interlocks and starter circuit |
| Cranks but will not start | Fuel, stop control, preheat, air and compression |
| Engine runs but no AC output | Breaker, excitation, regulator, alternator or transfer system |
| Starts then shuts down | Recorded fault, oil pressure, coolant or exhaust temperature, frequency |
| Trips under load | Overload, short circuit, motor startup, voltage or frequency instability |
| Overheats | Raw-water flow, closed coolant, ventilation or overload |
| Wet exhaust changes | Intake, strainer, impeller, anti-siphon, injection elbow or hose |
Before resetting a shutdown, identify the code and preserve evidence. Automatic protection may have prevented a fire or engine failure. Never bypass a low-oil-pressure, temperature, exhaust or overspeed shutdown for continued operation.
AC measurement around a live genset belongs to trained, appropriately equipped people. Even when the engine fault is simple, source switching, capacitors, rotating fields and inverter integration can remain hazardous after shutdown.
If extended cranking is required, manage the wet exhaust exactly as the generator manual directs. A non-starting engine can still pump enough seawater to fill the waterlock and flood a cylinder.