That is all interesting information. To clarify, yes it is a shutdown condition. The Onan panel is in place whenever it is run. The code displayed inside is fault code 36.
I got it back from the dealer because we have our first outing this evening and we'll be running on shore power. I tried to run it back at our storage unit with the access door open with the coach engine on. It only ran for about 20 minutes before shutting down. The service tech said that they were able to run it for about 1-1/2 hrs with the access door open...I didn't ask if the coach engine was on or not.
Ugh. I can see this is going to be a frustrating one. I'm not doing anything weird or unusual. Prime fuel, then hit starter. It cranks, starts, then let it run for a couple of minutes before putting a load on it. The area I've been parked is just a fine gravel surface that is relatively flat. The load is pretty much just the front AC. No fridge, water heater.
Additional info...it did shutdown for the service tech with the access door closed. He said he pulled the fuel line and ran it into a container. He got bubbles from vaporized fuel (post shutdown).
I had the same problem on my 2012. Exactly as you described. It was the fuel pump. Changed it and no more problems. I'd take it to Cummins as it's still under warranty. Good luck and safe travels.