the 99 surburban i know of has 150k on the original GM pump and its been whining as long as i can remember. its not that crucial i dont think.

 

or you have an aftermarket fuel pump, doubt it since it wasnt makign that noise the whoel time

 

I have read that the loud fuel pump was due to the bearings. This noise can be helped by using one of the following mixed 1 oz to 5 gals of gas for a few tanks: Lucas UCL (upper cylinder lube) or Marvel Mystery Oil, or FP60

Chris