Noisy fuel pump

[dschloz@wagstaff.com]

O.k., so after suffering embarrassment over the "spare" CIS-E fuse debacle, I
have to ask:

My 4ksq fuel pump is making an intermittent buzzing noise, especially at idle
(of course, I may not be able to hear it when I'm running--one of the drawbacks
of a 2.5" exhaust). I have replaced the pump inlet trap and the fuel filter, and
they car runs pretty strong, but I'm afraid the VW fuel pump the previous owner
replaced the original with is giving out.

Before I lay down $190 for a new pump, could this noise be caused by a dirty
tank screen? It is the only thing I haven't checked in the fuel system for
blockage. Also, are there enough differences between a VW fuel pump and the 4ksq
(i.e., discharge pressures or pump volume) to warrant replacing it anyway?

TIA

-Dave