★ Desperate Need Of Help ★

Ok. after further checking...

The main relay in the engine bay has power with the key on, like its supposed to. The other relay (under the dash) is getting power when the key is on... but its only to one port, the center one. I am having trouble finding the information on that relay.

I put the meter into the harness where it plugs into the pump. when I crank the engine over, there is power at the pump... as soon as I let off the key there is NO power to the pump.

 

OK, lets break shit down for a bit, I can tell that you're getting frustrated & you are starting to overwhelm yourself with potential trouble areas ( I know this because I do the same thing on occasion) So, 12v directly from battery to pump & all is well, voltage right, pump pressure building & holding on its own, as far as the "Dim lighting" of test light to connectors remember that we are in the world of ELECTRONICS now i.e; COMPUTERS & COMPUTER type voltage. Not everything on vehicles these days is 12v nor is DC "negative" always a common or ground, Dim test light probably means you are in an area that is reduced DC voltage(3v-5.5v etc & dealing with milli-amps , starting to sound like a PC yet ? As far as relays go you need to REALLY be sure about their normal function i.e; some are "normally open" to function which means that voltage & amperage is being "held back"
til a predetermined time when some other device lets it know that its ready to pass current, or some are "normally closed" which means that this relay is to remain closed to complete a circuit for normal operation. Dude, I was just looking thru a manual I have & I gotta tell ya that there is more shit & places in the eletrical/electronic system that this problem could occur, I don't know if yours is an OBO-1 or OBO-11 system because the system troubleshooting procedure for each is different. I think you have thrown enough $$$$ & definantly enough time at this problem that it may be time to do the unthinkable..... Take it to a reputable repair shop. I mean fuck, you've got fuel delivery (maybe water in the gas tank? ) to consider, pressure regulators, shit like that, electrically & electronically things to consider & we haven't even addressed the Emission sys. yet & what role it may play. & one other question I have is ... WHY IN THE FUCK DIDN'T YOUR ENGINE THROW A CODE ????(check engine light) Has your wiring been jacked by some back yard stereo or car alarm install ? maybe onboard CPU loose ground ? I dunno I'm gonna walk away from this one, its giving me an ulcer & I'm starting to stress on it more than you Bro' lol....

 

^hahaha... I now feel 10x more fucked than I did 10 minutes ago...

My friend that has been helping me is a certified mechanic. He can make sense of those wiring schematics that look like ancient egyptian hieroglyphics to me.

I am kinda leaving this issue to him for the time being. I gotta walk away for this part of the problems because I am about to start parting out the truck.