Troubleshooting a Generator
This may be old information, but I learned something about troubleshooting a generator that cranks, but dies after a minute or so.
My Onan would crank run anywhere from a few seconds up to a few minutes. After checking the normal things, fuel, spark etc. and reading all the post here on others having the same type trouble, I decided it was either the control panel or voltage regulator.
I down loaded a copy of Flight Systems troubleshooting guide. However, the guide wasn't too helpful (to me) since I am not that good with a mulitmeter. I called Flight Systems and a gentleman named (I think) Dan told me a simple test to perform.
Make sure you have a 110V light (lamp etc) turn on. Crank the ginny, and when it dies, if the light quits burning suddenly (like you turned off the switch) it is the voltage regulator. If the light goes dim as the ginny shuts down, it is the control panel. Now, this test is assuming you have isolated the problem to either the control panel or voltage regulator. Neither being cheap.
As Dan explained to me, the control panel controls the engine. So if it (control panel) malfunctions, the generator is still ginning as the engine dies. On the flip side of the coin, if the regulator is bad, the generator will quit supplying power suddenly, hence making the light shut off as if a switch was flipped.
Maybe this all made sense - it did for me and worked. I bought a new regulator and it solved my generator problem.