Well, tonight I think I may have found the problem. 0 volts going to the rear pump.
When I turn on the power on my car, the fuel pumps run for 20 seconds. It sounded like the rear pump was working, I just figured it was maybe dying. Turns out, it wasn't running, what I must've heard was the sound of it spinning as the front pump pushed fluid through it.
Ran a new wire to it tonight, we'll see what happens tomorrow.