My generator uses fuel from the fuel tank that supplies fuel to the coach engine. When the tank gets low (1/4), the generator will cut off. Thus, leaving enough fuel to enable me to get a station.
However, most likely, your voltage regulator went out. My generator was running, supplying current to both generators on a very hot November day and suddenly cut off as if I had switched it off. I discovered the voltage regulator had quit. I ordered a new or rebuilt one from "flight systems". It isn't a big job to replace.
I don't know if you have the same problem or if it is something else. Good luck.
Me & my Hun RVing for fun!