Onan 4K are notorious for simple issues causing problems.
The very first check you need to do is start it with the remote but do NOT let go of the “start” button when it starts.
If it continues to run, hold the button for 30 seconds then let go. If it stalls right away again, then get a known good battery or another vehicle and put booster cables on the house battery and repeat the same test again.
If it continues to run with the booster cables the voltage in the house battery is too low. Charge or replace it.
If it doesn’t continue to run, it’s a fuel issue.
