fuel pump noise

[m33bp]

I guess about a week or two ago, I noticed a whinning sound coming from the back of my Z. It was off and on and seemed to only happen when I slowed down. I figured it was the rear brakes. Upon inspection I discovered the brakes are fine and that it was the fuel pump.
The noise seems to me that it only happens when the fuel level is below half and is not all the time, but it has become a more consistant noise now.
I had the fuel pump replaced about a year and a half ago. I typically use 91 octane but have been using 88 (Conoco/Phillips 66).
I use the car mostly as a daily driver and drive about 30 miles a day to and from work.
I haven't noticed any difference in MPG or power, not stalling or stuttering at all. About the only thing I have done recently is run a fuel system cleaner through it when I went on a long trip, but the noise was there before that, but it has gotten worse.
Any ideas about this?
Thanks Matt

[DaveH71]

Try throwin on a new fuel filter, old one might be clogged and might be makin the pump work harder. Worked for me when i first got the car and tuned it up. The pump was was whinning really loud and i replaced the fuel filter and it went away so give it a try there only about 10 bucks.

[m33bp]

Any recommendations for fuel Filters.
About they only kind I can get here is Fram and STP's does it matter?

[FANTA-Z]

Nah you should be ok with either one.

[m33bp]

Cool, I will just get the Fram. Thanks guys, matt

[DaveH71]

Anytime man, just let us know if it fixed your problem or not

[m33bp]

Update!!!

Replaced the fuel filter, thing looked gross, but I still have the whinning noise coming from the back. I can hear it now when I have a full tank of gas, and although it isn't constant, I am really annoyed/concerned about this.
Other thoughts. just a reminder fuel pump was replaced about 1 1/2 years ago.

[DaveH71]

Ive always had this problem with my chevys and ive heard of it alot from other people to, its not bad its just annoying. My pump on my 98 s10 i used to have whinned like a stuck pig but that truck ran like no other, never had a problem with it. If you cant bear it anymore or you just would feel better get a new one there not to expensive and you might aswell get a good performance one wile your at it. I read somewhere theres a way to replace it without dropping the tank. Lemme look around a big and ill post back if i find the article

[DaveH71]

Forgot to mention, before you go looking for another pump or anyting try running some REDLINE fuel system cleaner in a full tank of gas sometime and see if that works. Its good stuff i used it before and its a great product. Its only about 7$ at like autozone or something.

[m33bp]

I've run Lucas system cleaner and no good, still whines, plus Have read about the cutting the hole in the back part to avoid dropping the tank, I am not sure if I want to do that, I suppose I will just live with it, but thanks for the advice, I will try redline when I change my oil, in about 2000 miles.