84 T2 Wiring gremlin

[W.P._Turbocars]

Setup:
84 Rampage
89 turbo mini harness
89 TBI Omni dash harness

Problem:
Had the truck parked a couple years total. After my swap from one truck to the other I have no fuel pump power unless the park lights are on. I know it makes no sense and I hunted and hunted for hours tonight and no luck. The only way to get the fuel pump on (it will not prime but stays on constant) is only if the park lights are on, either by turn indicator or light switch with the key in the "on" position.

Anyways guys maybe someone can post up some info by tomorrow afternoon. I'm really tired and calling it a night.
THanks for the help guys.

[Scamp_GT]

Obviously the power to the lights are jumping over to the pump. does the lights turn on?
I'm kinda thinkn since the only way to get power to the pump is to turn the ign. switch.. the lights power going to the pump and no power to the lights. Faulty wiring??

[black86glhs]

Sounds like the terminals in the fifty way bulkhead connector don't match between the omni and the the van harnesses.

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[W.P._Turbocars]

It was fine and had been run in my 82 with no issues for about 3 years. All I have done is pull it from one to put in another. I'm still thinking it's a ground problem. I am gonna double check tomorrow as today was a pretty crappy day overall. :(

I'll report back after tomorrow... Hopefully with a vid of it running. :thumb:

[black86glhs]

It was fine and had been run in my 82 with no issues for about 3 years. All I have done is pull it from one to put in another. I'm still thinking it's a ground problem. I am gonna double check tomorrow as today was a pretty crappy day overall. :(

I'll report back after tomorrow... Hopefully with a vid of it running. :thumb:That rules out my idea....lol. A ground sounds plausible. (thanks Mythbusters) I have seen them cause all kinds of weird crap.

[W.P._Turbocars]

OK. I got the fuel pump to work. I traced everything with no luck and was about to give up when I decided to swap the computer out. Now I have a fuel pump! Still no crank though. I traced and traced and no luck. For some reason I focused on the backup light switch and that's where I am getting lost. If I take the purple wire coming out of the backup switch and piggyback it into the ground wire on the started harness it cranks right over (but no spark) If I take that same purple wire and ground it straight to the battery it won't do anything at all, only when it's piggybacked into the started subharness ground.

Another thing I can't figure out is why when I run my test light to EITHER side of the battery TO the ground wire on the sub harness it will make my test light come on. I even have the ground from the subharness ran straight to the battery for it's ground.