Onan generators are fairly smart devices.. First, once the unit has started and stopped,, Tap the STOP button and count the flashes of the light,,, Write it down and then count the next group of flashes, Continue until the pattern repeates. (you will get a much longer pause before the repeat).
Look it up in the troubleshooting manual.
Some of the things that will kill an ONAN once you release the start button.
Low oil/bad oil level sensor
NO AC OUT, note that this is measured ahead of the circuit breakers.
Partially clogged fuel filter (Runs a few seconds and dies) or other fuel line issues.
Air filter issues (same thing)
and a few other computer detectable issues... I can not list ones I've not had either on an ONAN or another engine.
