Well this is funny, I took it for a drive around the industrial park, noticed some power surging when it was cold. Then it went away after a few minutes.
I get back to my parking lot, decide to sump the fuel in case there were any contaminants/water in the filter housing, truck dies as soon as I pull the sump lever, absolutely no fuel came out either… I was low on fuel so I added 5 gallons in case it got low enough to not reach the pickup in the tank. No luck, won’t start again, no fuel coming out of the sump drain either. No leaks in general around the entire truck.
I figured one of 2 things:
1: Fuel line clogged before the filter
2: Mechanical fuel pump dead
Luckily I was already planning on changing the fuel pump given the age on the existing one, along with some tiny drips I saw several weeks back, so I already had the parts ready to go. I swap the pump and the truck starts up instantly after a few cranks.
In terms of observations between the new and old pump, the black plunger on the new one was much stiffer than the old one. Nothing much else looked different.
I guess when I initially opened the sump, it lost whatever air pressure was keeping fuel flowing to the IP and caused it to die.
Fun stuff, pics attached