Onan 4.0 Turns off after few hours

[Quest]

Hello IRV2 community.
We just got this vintage Onan yesterday from Craigslist.
Onan 4.0 RV Genset
Model BFA-IR / 15004C
Serial K803 533630
We tested before removing it from a MotorHome and and did run fine for a while.
We got it to our place and got it connected and everything did run fine for the first 6 hours and then it turned off.
Oil Level : OK
Fuel: Fresh and New.
We fired up and same thing after 5 hours.
Fired up and same thing after 2 hours.
Any clues?
We order the parts for oil change and Air Filter.
The generator runs fine and smooth but when the AC Compressor kicks in it sounds like is struggling to keep it running for about 3 to 5 secs.
Any advice?
Thanks

[Francesca]

Hi-

I don't know the smallest thing about generators, but...
You might want to check out a new "Onan" thread here- sounds like a similar problem and the poster did get it fixed...
Here's the link: Just FYI Onan generators

Good luck!

Francesca