Perkins 4008 over speed problem when we change the wood ward controler

1. Fault phenomenon of diesel generator overspeed

Under normal operation, the engine speed suddenly rises, so that the engine speeds up beyond the rated speed and loses control, and emits a huge roar, the exhaust pipe emits a lot of black smoke or blue smoke.

2. Cause of failure

The fundamental cause of diesel engine overspeed is that diesel engine loses or changes its speed regulation characteristics. Faults of fuel injection pump and governor, such as stagnation or looseness of relevant components, will cause excessive oil supply and loss of normal speed regulation characteristics, while the combustion chamber entering additional diesel or oil will change the speed regulation characteristics of diesel engine.

1) Faults of injection pump and speed regulator
2) Additional fuel enters the combustion chamber
3. Solution to overspeed fault of diesel generator set
...
https://www.dieselgeneratortech.com/diesel-generators/The-cause-of-overspeed-in-a-diesel-generator.html

Check the mag pickup sensor on the flywheel for dirt chips of metal.