To answer replies so far: my generator is an Onan Quiet Diesel, 7500. It has never failed to start, until this trip. My house batteries have never been boiled dry but they do test a bit weak. Not surprising since they are more than 6 years old. When I tried starting it, it seemed to be turning over a bit slow. After we drove for an hour, it spun normally and fired right up. I believe the generator starts from the house batteries. Incidentally, my awning is also slow to come in and will not retract all the way without help. I believe this indicates weak house batteries. Am I right?