Stranded at 10 below
 

So I fueled up 30 miles ago, driving along through the cold whiteness, and the engine sends out an almost imperceptible hiccup. A couple miles later it's a hesitation, another mile, and it's a hop, and within a total of seven miles it's a full-out limp. Got to my destination, idling nicely, and shut down at ten below. Had a goat to disbud (burn off the horns, you know?), and when it's over I get back in. Starts up great, but no power. Headed the 37 miles back to town but only get one nasty, gagging, hopping mile before I'm dead on the road.

Towed it to a friendly garage and came back a couple days later. Started fine - convinced me after 30 mins that I could chance it home, and then it died. Crank, crank, crank, nothing. Towed back to garage with my Subaru (oh, the ignominy) and came back a couple days later, assuming it was a fuel problem. Dropped the tank, no water. Found some strange, flat, potato-chip-sized paint slabs in there, likely from the bottom of the tank. Took them out. Wiped it clean and dry and reinstalled.

Tested fuel lines for pressure (yes) at the heads, changed fuel filter. It restarted, and I immediately took it home, hesitating all along the way, at just above freezing. If I pressed further on the accelerator pedal it smoked and smoked without power and had a clicking sound I'd never heard before (maybe because the cylinders weren't firing?). It got worse and worse, and 25 miles later felt like I was running on two cylinders before it quit. Had to borrow a parking space.

Came back a couple days later and started up cold, again, near freezing - seemed to still run hesitatingly. Added fresh fuel, and it felt like it ran better (wishful thinking), but it later stranded me again, this time after trying to start when hot.

Started it cold one more time, hiccupped my way home back up my steep hill, resolved to replace the fuel pump. In the process I broke the IPR connection (wouldn't start and threw a P1283 code to show me that one). There's a new pigtail on the way to fix that. There was a rear ABS code I'll fix later, and a P0603 code.

I cracked the fuel lines at the head to make sure there was fuel, but I'm not entirely sure there wasn't some air in the lines even after 30+ miles? Could air still be in the lines?

Ready for things to get better...

At first I was wondering how you broke the IPR when replacing fuel pump, but then I realized it's an older non super duty 7.3 with the mechanical pump in the valley.

When you checked fuel pressure, what was it at? And at WOT?

When you dropped the tank did you perform the hutch mod or look at the mixing chamber screens?

I know I have read a few issues with the van tanks being "painted" from the factory and clogging up the fuel tank screens and system down stream as well.

You got it right - in order to connect the fuel pump lines to the fuel bowl I needed to shove the bowl forward, and in doing so I'm assuming I ripped out the electrical connection. Gentle, aren't I?

Didn't check the fuel pressure. I guess it's incidental at this point because I've changed the fuel pump already.

I'm really new at this, so I don't know of any mods. I do know this - the whole pickup/sender/return line assembly came out of the hole, and I wrapped it in a clean towel and laid it aside until reassembly. I inspected the pickup screens - looked reasonable to me. I did find the fuel filler part (that I suppose prevents fuel backsplash) had fallen into the tank, and I replaced it at the tank side of the filler tube.

At any rate, I'm now replacing the IPR wiring (another post today), if I get it right (the colors are not the same), and I'll see if the replaced fuel pump works.

I found a Schrader valve on the side of the fuel bowl, so I suppose a regular pressure gauge reading around 100psi will work?

Finished fixing the IPR connector. Restarted after the fuel pump replacement, and it ran just as it ought.

Problem solved.

This has certainly been an education in a diesel fuel delivery problem and its symptoms.

Well, that's good news, and good times getting an education.

Do you think the IPR connector might be the cause of a P1670 code I have now?

Pretty sure 1670 is one of the codes that comes up when there's a communication problem between the PCM and IDM.