fuel pump noise?

[Andrei Kogan <abk@phy.duke.edu>]

There have been a few posts regarding noisy fuel pumps recently.
Can someone describe to me what it sounds like when it is about to go bad?
I hear a fairly loud  noise from
the back (the car is still, engine running) which wasn't there before, 
it  sounds almost like an engine fan working in the 
trunk/ backseat area. It seems to be  different from the regular fuel pump
buzzing away sound.
If it's not the fuel pump, what else is in there that could be doing it?

The car doesn't show any loss of performance. If this is  a fp, do I have
another 2-3,000 miles 
before it goes?

THanks, Andrei