Onan Microquiet won’t stay running

I too have problems with an Onan MicroQuite 4000 speck "J". Checking AC Voltage at main (unit's) breaker to base ground I get 26-48 Volts????? Slip rings cleaned, brushes good, rotor tested, stator tested, unit runs great. Any help would be greatly appreciated!!! I'm thinking the control-board is bad but would love to test all components before playing "Parts Swapper" I have the KY Service Manual but it doesn't cover the "J" spec unit???

I suggest you check out the SmokStak forum for expert advice on diagnosing and repairing an Onan:

https://www.smokstak.com/forum/forumdisplay.php?f=1

Steve

Thanks for the reply. I haven’t had a chance to tear into it yet. Hopefully I get a chance to attempt to diagnose it tomorrow. The unit is in a living quarters horse trailer so the mounting location of it allows access to the flywheel side of it and the ability to pull the top of the housing off. Will I be able to pull it or do I have to remove the unit from the lower plastic housing assembly to allow for clearance?

if you get a fault code 32 (low cranking speed) but the engine seems to be cranking at normal speed, then the problem is in the generator. The control board reads speed from the a.c. sign wave generated in quadrature windings in gen. stator. if no power being produced in gen., then no signal to control. most likely causes; bad field brush contact at rotor slip rings, open rotor winding, or open stator (quadrature) winding. Also possible the control board bad. Unfortunately, the brushes are somewhat difficult to access on this model genset. Flywheel must be removed, to get to brushes, which of course means genset has to be removed from vehicle

I went back and checked again and realized I was doing it wrong. There is only a code present if I continue to hold the start button until it shuts down on its own and that code is a 32(low cranking speed sense) which I think doesn’t mean anything as it sets when it shuts itself down. I was pushing the button 3 times with the misunderstanding that it would give me a code but just flashed 3 times and was reading that as a code 33.

Look here code 33