Fair enough, but the ambient temperatures around here are over 100*F. When relieving the fuel pressure at the rail (schrader valve), the fuel coming out was pretty hot. Regardless, my friend who is a fuel injection engineer happened to be with me and helped me diagnose the issue. The fuel was getting so hot that it was vapor locking the line; the truck eventually stopped running. There was also a substantial amount of pressure built up in the tank itself. I'll be getting a vented gas cap for sure.
The pump still works and the truck still runs, but the pump doesn't sound healthy anymore. I think it was damaged from the vapor lock situation so it needs to be replaced.
'89 5.0L: 8.4:1 Dart 304, Crane 2031 cam, GT-40 lower, KB Blowzilla 2.2, LMAF, 90mm TB, 42# injectors, TwEECed A9L
'79 Bronco on 35s & 4" lift: 8.5:1 408M, Crane 523902 cam, GT-40 lower, Cobra upper, Cobra 70mm MAF, 65mm TB, 30# injectors, EDIS8, TwEECed A9L, single O2
'08 Buell XB12Ss: stock 10:1 1203, Drummer SS, '10 header, independent O2s, K&N filter, 3 bar MAP, DDFI3 tuned via TunerPro RT