Humming sound from rear of my 2000 Chevy Blazer.

valleppa

what could be cause

cel2001

Could be from the ring and pinion, axle bearings, fuel pump getting weak, is it constant or change in pitch as you get to higher speeds?

valleppa

just had fuel pump replaced not that at higher speeds can hear it less

Mr_Shiftright

Also have a look at your tires--if there is any "feathering", that can make a tire very noisy.

One test---let off the gas--is the noise still there?

valleppa

tires are new and not feathering  must be wheel bearing.

Mr_Shiftright

Hard for us to hear the noise of course. Wheel bearings are more like a "ball-sy rumble". If the noise were higher pitched, like a siren, then more likely ring and pinion and usually make noise only on "pull".