Buzzing from rear of car...AND... tire unbalanced?

My fuel pump is always really loud buzzing, maybe that is my problem! I had a vibration at higher speeds and it turned out to be a loose driveshaft bolt, something to look into.

Sounds like the buzzing noise is the fuel pump. The vibration could be flat spots on the tires from sitting... Only way to find out is to get them balanced.

A buzzing fuel pump usually means it's about to die. I will say my new pump buzzes but it's aftermarket and I've heard lots of aftermarket pumps buzz. My blazer would whin a lot and it was stock. My original pump on the stang buzzed for two days and died (sounded way different then the buzzing I'm talking about with aftermarket pumps).

I can't really tell you what is wrong with the rear end. Now that you said you were "roughing" around on it, you might of done some damage to the rear end mounting points. Could of harmed; upper control arms, lower control arms, torque boxes.......

I'd put it up on some jacks and check-
1. rotate the tires by hand and see if there's some high spots or if a tire has seperated
2. check the mounting points for the upper and lower control arms



Fred

Is it buzzing more with less fuel?

The lower the fuel the louder the pump will get - IT IS BAD FOR THEM

If this is the case you might want to fill it up sooner. If it's all the time then replace it before you get stranded. It's super easy to do.

As for the vibrations... Not sure what the heck you did you to your car but it sounds like you screwed it up somehow - I'll leave that one for everyone else to answer.