[Rich Biebel]

A 1999 model is probably the old design. Flathead engine. Does it have a black sheet metal cover? Big square type box? They made a 7000 Marquis back then. The best unit they ever made......Electronic governor, quiet 1800 rpm.....

If it is the old design they did not have the self diagnosing feature of the newer design units.....

Onan parts prices are pretty high and they are owned by Cummins....

I have seen a lot of bad fuel pumps on many different models. I don't doubt the fuel is killing some of them....