1984 B2000 won't run

Alright guys I have an issue and can't quite figure it out. I have an 84 B2000 with the 2.0. I am in the process of putting the motor in and getting it to run. I had everything working great but now for some reason nothing on the truck is getting 12 volts. The fuel pump won't turn on unless hooked directly to a battery. I have swapped the check relay and 3-point relay and that didn't change anything. The battery is new. Anyone know about the wiring in theses and why nothing in the truck is getting power?

Maybe the grounds need to be checked or the cable ends have corrosion in them. That would cause a really high resistance and that might be where the problem is.

Battery cables are good and grounds are good.

You check the ignition switch?

Have you checked the fusible link. It was on the right fender about 3" long and 1" wide.

When are you checking your fuel pump? With just the key turned to the on position or while trying to start the engine? Have you unhooked your fuel line and see if it primes when you turn the key on? Or are you just getting no power ever to your pump even when trying to start?