Onan generator only runs with switch held in

Try starting the generator with the van engine running. Leave it running for a few minutes after the generator starts and stays running. I have found that if the Roadtrek batteries are low the generator will either not start at all or is hard starting. Make sure that there is nothing turned on inside the Roadtrek to take off all power loads when trying to start the generator and it is hard starting. Make sure the A/C switch is off, unplug the microwave. While this is not so much of a problem when all is well, when the generator is not starting this can be one of the problems. Also do you have more than a 1/4 tank of gas in the van? The generator will not start or run with less than a 1/4 tank.

Once you do get it started you may find that if you turn on a power load soon after starting it will stop again. Let it run for awhile before adding a power load - when it is hard to start.