Hello: New to this site. working on my buddies 97 boneville. We had no fuel pressure so i put on a new filter and pump. No help. Engine will run for about 3 seconds and die out. If you hit the gas the engine will die faster. I've heard that the oil pressure switch may be bad, it has a full oil pan so it'* not low on oil. I've also thought about the fuel pump relay but that doesn't make too much sense to me since the pump comes on just fine. It just shuts off once the key is turned over.

Any ideas would be nice.

This model is not supercharged.

Sounds like a VATs problem to me. Are you using the chipped key?

Sorry man, dunno what you mean. I'm assuming thats some sort of diagnostic tool which I do not posses.

Take a look at this write up, hope it helps.
https://www.gmforum.com/t279119/

Sounds like a lot of work, but I can definatly try it. Is it possible that the oil pressure switch is malfunctioning since the fuel pump is wired in-line with it. The pump will come on till the car starts and then when this said sensor should take over the car dies along with all fuel pressure.

I just want to head in the right direction.

What does the fuel pressure gauge say? Changing that sensor is easy and don't cost to much if you want to give that a try. Not sure if that would shut down the engine, don't recall anyone ever saying that

I don't have a gauge, but pressing the test port while key is on shows a definite drop in the pressure from spraying out fast and hitting the front of the car to a small flow that is dieing off.

Key on only primes the system, the behavior you describe is considered normal.

That'* what I thought but I have been told otherwise, but I guess not by reliable sources.