In order to come up with reasonable guesses you should probably provide us with the year and make of the coach, chassis and engine combination and anything that has been done to the coach recently. That said it's likely a fuel or ignition problem. Do you get fuel to the carb, throttle body or injectors? Do you have spark. The engine and the genny probably have different fuel filters so one of them may be clogged. Have you had any stumbling issues recently? In short, we need more information.
An Old Fisherman
2017 Nexus Ghost 36DS, 2004 Ford F150 Long Bed
2007 Harley-Davidson Ultra Classic