Son of Norway wrote:
Google "Flight Systems Onan generator troubleshooting guide" and download a copy. It's the best troubleshooting guide that I've seen. Also contact your Cummins/Onan dealer and get a copy of the Onan Marquis Service manual. The Onan manuals are excellent. Hard to know what your problem is just based on your description. Did you try both the inside switch and the switch on the generator?After you follow rk911's advice, grab a multimeter and start going through the Flight Systems guide.
WOW. I had a 1988 just like yours. Brings back a lot of memories. They were so much better built. I had a factory OEM ice maker in mine. Enjoy