1996 Suburban fuel/electrical problem

Hope I can get some ideas from anyone...because I'm idea'd out.

1996 Sub w/5.7L, "Check Engine Light" came on, no usable codes pulled up by AutoZone. Disconnected battery overnight and light reset. Truck ran fine for a couple more days. Engine light did not return. Started truck and then went to run inside, truck died. Will crank, but will not start. No sound from fuel pump...checked fuses, replaced pump relay under hood. still no joy...replaced fuel pump (old one would not run with direct 12v applied) and fuel filter. Still nothing from fuel pump. Changed oil pressure sensor, no joy. NOW, there's no power to the chassis plug that connects to the fuel pump assembly (went to all three pins, one at a time, and other lead to ground with key "on"). 12v to relay legs 85/86. Many, many thanks in advance.

Check underhood fuse ECM-B to see if its good. You may be able to find the fuel prime conector between the under hood fuse panel and the firewall, its a red wire with a spade connector on it and it may be sticking out of a wiring harness loom or taped to it. With the ignition off, applying 12v to the prime connector should run the fuel pump. The grey wire should have power at the pump with the fuel prime wire energized(grey wire at oil pressure sensor should have 12v also)

Jeremy..Thanks for the feedback. Turned out to be a bad ground on the chassis plug (fixed that and had 11.6 to the pump) and the connector at the top of the sending unit had heated and checked good continuity, but wouldn't carry the voltage. Replaced the sending unit and it's back on the road. Appreciate the help!