His vehicle has been leaving him stranded QUITE often and I cant figure out whats going on. If it sits overnight it'll start right up and run for quite some time....then die.

I've determined this much.

He's replaced the fuel pump 2x in the past 3 years. (he's on his 3rd pump)
After it quits running and you turn the key to the "run position" you can hear the fuel pump run constantly.
After the no start and the pump constantly running, when you turn it over it gets NO fuel to the injectors.

What I'm not understanding is how the pump is working....then not. When it stops working (pumping) it's like it's just trying REALLY hard to catch a prime.

Any ideas? Thanks in advance!

Edit: Oh, and....it's a 2-bbl TBI

I would check the relay.