That'll freak you out. Most of the time we can't get them to start, but none of the switches would stop it, including the kill switch on the genny itself.
Here is what had happened. There is a solenoid close by the mechanical injector pump that opens or closes a valve which controls fuel flow right at the injector. The control rod from the solenoid to the control arm had come loose. A Ha ! Found two nuts of the right diameter and thread pitch in the workroom, and put them on with Loctite.
I could just see calling the emergency line at Newell with a "uh, I can't turn off my generator, what do I do now?" I was looking for the electrical leads to the fuel pump when I saw the loose control arm.
Richard Rhonda Ty and Alex Entrekin
1995 Newell # 390 DD Series 60, Allison World Trans
Subaru Outback toad
Often wrong, but seldom in doubt
Rhonda's chronicle https://wersquared.wordpress.com/