98 Malibu 3.1 Howl or Whine noise from rear?

I have a 1998 Malibu with 133,xxx miles on it and for the last few years it occasionally has a loud howling noise that will last for a few seconds and then go away. It is fairly loud and kinda obnoxious at stoplights. If I get out of the car, it sounds like it is coming from somewhere just ahead of the fuel tank in the rear center of the car. Any suggestions? Thanks.

It is probably the fuel pump. Mine did that right before it started to fail. I knew the fuel pump was failing when, after letting it idle for a couple minutes with the fuel pump wailing, it stalled. I had the fuel pump replaced and it did not stall again.

However, the replacement fuel pump whines on hot days after being driven 30 minutes or more. I look at it more annoying than serious as it has been doing this for over 40,000 miles with no other issues.

Thanks for the input. The fuel pump is the only thing around there that could make the noise, but I figured it would have failed long ago if it were the culprit. Guess I have the same fuel pump you now have...