Onan 5500 Randomly turned off and won't restart??

Check oil level to see if it is low. If oil level and fuel is fine, turn off breakers and try to start again. If it works, you have an electrical short that shutting the Onan down.

I used to run my generator twice a month, so I never had problems with gas sitting in the carburetor and varnishing up. If yours has been sitting more than a month, you may be experiencing clogged jets or bad gas.