After a couple years of parts checking, parts changing, and minor improvements that always became temporary, the truck no longer loses prime when sitting with 1/4 tank of fuel and is back to starting after turning over about 1/4 rev!
Yup, it was the connection pin(s) in the fuel heater. It never leaked and was dry when I unplugged it. I thought it might be because of the oxidation between the sediment bowl and the o-ring but after I cleaned that up and disassembled the heater to check it, I could hear the leak when it was under vacuum after I got it all back together.
The heater is now holding down the box of spare parts on a shelf. My question is directed to those who have removed this high dollar techincal marvel (POS) and ran through a winter without it. Can I run without it and not have problems? Bear in mind my location, the fact that it gets -20 here sometimes and I might be up north sledding and can't always plug the truck in.
I replaced it a few years ago because the harness was burned up (could buy ***'y only, no parts available then) and the truck was running bad in the winter. A few weeks later I replaced the fuel solenoid so it could have been a weak pull-on coil that caused the power problem.
One more note: the part number listed in several posts for the heater o-ring (3834185-S) didn't come up as a current number at the local Cummins shop. Anyone have an update?