2001 Duramax Losing Prime

[horsecamper]

"Whitey" has just started losing prime after sitting a few days. Not realizing what was going on, I had "Whitey" towed to DSU (Phoenix, Duramaster, not Portland). DSU checked all of the lines for leaking and was not able to repeat the losing prime, even after sitting over the weekend. DSU suggested driving it for a few days and doing a recheck on a possible leak area. After returning home and being parked a couple of days (slight incline, nose up), I again lost prime. I'm now losing prime quite consistently after sitting for a few days. I'll be going in to get a recheck on the possible leak area, but, in the meantime, I thought that I get some feed back from ya'll. What all parts problems has everybody experienced that lead to the "losing prime" condition? In my case, the fuel filter is probably not suspect. It was changed 1,181 miles ago and I just started seeing the problem. Also, is the losing prime condition always experienced at start up after sitting for a few days, or does it also happen during periods of prolonged idle? And, if so, are the root causes of the "losing prime" different depending on whether it fails at start up or during periods of prolonged idle.

[DmaxMaverick]

Replace the fuel cap. It is relatively cheap, and could be a major contributor to your problem. Be sure to get a "Diesel Fuel Only" cap. Gasser caps won't work.

Don't rule out your filter. When they leak, it's usually shortly after a change. The O-ring(s) should be reseated, and use some dielectric grease on them during the install.

[OC_DMAX]

If the fuel filter was just replace 1K miles ago, that would be the place I would look.

When my truck was new, I had a similar situation. If it would sat for a couple of days and it got extremely cold outside (from a So_California perspective), the truck would loose prime. Turned out the filter was not completely tightened down from the factory. I took it off, put it back on again, tightened down on the filter and everything was fine from that point.

The filters are relatively cheap, I would just try replacing it (or if nothing else, make sure it is tight).