I have a 95 Z28 with the mods in my sig. My car for the last couple of weeks has felt like it has no umph in the top end rpms, then this week-end, it had a crazy rapid fire backfire in the top rpms.. It would backfire like 4-5 times in a span of a couple of seconds under hard throttle.. I quickly get off the gas when it happens, and it also seems like it stumbles when I take off from a stoplight if I have been sitting there for a bit… I don’t really hear the fuel pump like I used to, could it be the fuel pump or something else? How do I check if it is the fuel pump? No engine lights and no other symptoms….Thanks in advance....

 

You could test fuel pressure via the Schrader valve at the back of the intake. Get a pressure gauge with a 4-AN fitting and test idle pressure and try to figure out a way to test the pressure under full load.
I would guess your pump is bad since you used to hear it before, because a noisy pump is a sign that it is giving up.

 

The sign that I got from my pump when it was going bad was that it had a weak initial prime. Then while starting, it took a few revolutions for it to finaly turn over properly.

 

Would a faultly fuel pump casuse bad backfiring up top on hard acceleration? If it's not the fel pump I don't even know where to start troubleshooting...

 

Maybe check how your fuel filter is doing?