Weellll, the end may be farther away than we thought. With the car seemingly running well, packed up the kids, dog, and loaded up the roof rack and drove 7 hours for a family reunion. Car did fine, a little slow on the hills, getting 23 MPG going through the mountains, then seemed to lose power in the last 10 miles of the trip, and would stall everytime I stopped from there on out. I just let it sit for a few days, then test drove it, and it seemed fine, again.

BUT, on the way home, I had much less power, and in the middle of West Virginia, it slowed to a stop. No amount of fiddling could get it running again (changed filters, even the tank screen), and had to get towed the rest of the way home. First time I've ever had to get towed. Ever.

In an effort to resist my urge to set the thing on fire, I parked it out back for a while, and am just now getting back to it. I've been tempted to just put it on E-bay and let someone else fool with it, but I have a hard time giving up.

So, it now starts, and can move under its own power, but is idling rough. I swapped in another lift pump, as it really seems like a fuel starvation problem (and since I had a spare sitting around), but that didn't make any real difference.

Picking back up on this thread, I dusted off my fuel pressure testing kit, and lo and behold, I'm only getting 6 psi in the line just before the IP. I pinched the return line, and got the pressure up to about 20 psi, and it seem to help marginally (maybe just wishful thinking).

In any event, now that I know I have fuel pressure problems, and having read some other threads on that issue, I'm thinking perhaps the relief valve (or in Bosch-speak, the "overflow valve") in the IP has failed.

Any thoughts?


Patrick Skelley
Bedford, Virginia
1970 Unimog 406
1972 350SL 4.5
1972 300SEL 6.3
1978 240GD
1979 300GD
1987 300TD