Onan Diesel Stumbles Only When Coach Moving

[DonBaja]

I have a vexing issue. My Onan 7.5 diesel generator stumbles, loses voltage (down near zero) and eventually shuts down when moving and especially going around corners. On the other hand it seems to run perfectly under a big load with the coach stationary. At first I thought it was the fuel filter/water separator, then maybe I had shorted batteries, but after further investigation, I get the same outcome with all appliances off, new batteries, and no load whatsoever. I initially drained the water separator (maybe a 1/2 ounce) and found no sign of water. I was hesitant to drain more as it might make it hard to restart. The filter was brand new 10,000 miles and a year ago. I have a replacement fuel filter/seperator on order. Any ideas?

[ernieh]

If it runs well under load, I think that I would be looking for an electrical problem like a wire harness or switch that shorts out.

[bigskymt]

Low on oil? As the oil is drawn away from the sump, especially on a corner you lose pressure which turns off the fuel pump.