Buzzing Noise From Back
GM fuel pumps are in general loud. I can hear mine from inside my car. My Chevy pickup was the same way, and so was my GTP. My GTP was the worst offender, it actually had a two speed fuel pump, and the lower speed was for when you were idling or sitting around, it was intended to cut down on the noise... but nope still loud as fawk.
Mine sounded like a tornado Siren when it started to go bad. When i replaced it with a brand new delco unit, it was back to its loud as fawk self.
if you are worried about the FP, put a fuel pressure gauge on the car and see what pressure you ahve


