batteries discharged very quickly and truck is dead

Digging up bones here, but that's why so many questions are (not necessarily here...) answered with "run a search!" Well, that's where I started and believe I may have found my issue.

mid-20's cold start this morning, glow plugs did their thing and the engine spun OK, *maybe* a bit slow, but I attributed that to the cold. Anywho, let it warm up whil I got ready for work, and about 30 minutes later I went out to see the truck on high idle, purring away, only oddity was the dome light going off when I opened the door (?). Backed out, radio was goofy/gabled on one station but played another (?), dash lights were noticeably dim, but were on max. Couldn't see my headlight on the road (uh-oh!), volt meter low, around 5-8 (big uh-oh!). Mad the rest of my 9 minute commute without issue, engine ran fine (turned off heater blower, radio), but electricals were all but dead, voltage at near zero, gauges dead, but it got me in.

The alternator is a few years old reman (I *think* O'Riellys), and wally world batteries are 3~4 years old.

I'm guessing the frame-mounted fuel pump isn't essential to an already-running engine? It certainly couldn't have been doing squat at those voltages!

Thought, suggestions?

Bob

 

Thanks, guys! Found the three bolts that clamp the sections together backed out, waxed the innards. Replacement time. Friggin reman monkeys.