Thanks all but it has to go to a person experienced in Onan 8K Quiet(ish) diesels. Since you asked.... We started with the well known "fuel pump won't shut off and engine won't crank" problem which a Generator guy on the mainland fixed temporarily by disconnecting the P-8 connector and cleaning it out. On the way back to Buxton we got a "no oil pressure fault and shut down". No it wasn't the oil filter. I replaced oil and filter and no change. We found that the previous owner had worked on the P-8 10 wire connector and reassembled it without any of the seals. It had been drinking windshield washer fluid for years. Contacts are screwy. Both of those faults can be caused by a bad ground anywhere from the dash to the engine oil sensor. I understand that I am as likely to do damage as to fix it. Don't want to throw a rod or score the cylinders.
The old timers at Smokestack spent a bunch of time with me and that was the conclusion. They know a lot.
Cummins Onan gets $170 an hour
but they will fix it. They will get every penny I have but it will be fixed. I just have to find one that has time or a similar shop with an Onan trained tech.