I have an Onan 5500 that has always started easily and run fine. Has about 240 hrs. I have a guy doing some inside work today so I showed him how to start it and turn the heat on as it was cold. He ...
With that many hours, I'm guessing a governor adjustment. If it was fine with a load, and quit as soon as the load was removed, I'm guessing the generator saw something it didn't like and shut down.