Yeah, I took the fuel cap off... still did it with the fuel cap off.
I'm going to pick up a fuel pressure gauge from Harbor Freight tomorrow.. i wonder if I can hook the gauge up with a T to monitor the pressure while the truck is running.
I ran it today and immediately after it died I popped the fuel line off the filter and fuel blasted out so there was for sure pressure in the line from the IP to the fuel filter. I opened the top of the IP and it was full of fuel.. I removed the fuel return line from the top of the IP and cranked it over and it flooded the valley with diesel fuel as it shot out of the top of the IP so it's for sure getting fuel to the pump... maybe it's not getting enough pressure? The mechanical lift pump is 100% squirting fuel with every rotation of the engine.
I read in one quasi related thread that there should be about 6psi out of the filter to the IP. I planned on checking that tomorrow to rule out a fuel delivery issue before I ordered the rebuilt pump on Monday.
My guess is the metering valve is all gummed up or sticking rusted advance lever and seals. Pumps are precision like a fine watch working at + 2000 psi injection pressures. Supply pressures of 3 - 7 psi OK. Lift pump should be able to fill 16 oz water bottle in 3 or 4.... 20 second cranking cycles at the output of filter to IP Pump. (yea, drain line works, but what's really going on)
Check and a deep clean with some solvents, might clear it up, might.
I point one to the easily read free overview for most of the questions that show up here. Section 3 for fuel.
Another guess, twenty plus year old pump, truck parked for 10, nasty fuel, only 180 miles on the clock (clue to send one down the rabbit hole)
Might start looking for a new pump too, Thank You, Camo