Not much info there but my guess would be the the fuel pump.
the humming noise is coming from a bad ground on you stereo
where is the humming noise coming from? if it's coming thru the speakers and matches the rev tone of the engine, then you have a bad ground in your stereo.
A computer tower may make a surging noise rather than a constant humming noise if the case's screws are not properly tightened. Another reason for such a surging noise is the imminent failure of a fan.
radiator fan.
is the humming coming from the front end of the vehicle? i have a 1996 explorer with the same issue. yes the noise come from the front but not all the time seems to make the humming noise when it gets hot
it sounds like a humming or whinning noise, what year is the truck if its from like 01 or up those trucks have a lot of wheel bearinig problems that some one might misdiagnose as a differential noise or it could be chopped tires making the noise.
Most likely the humming noise is coming from a contactor located in the outdoor unit if you hear the noise outside or from the air handler or furnance located inside the home,if the hum is inside the home
Answer Humming noise from front endI just got my car fixed with the same problem and it was the wheel bearing and it is gone. Was it a fwd car?
its probably your radiator
It's the turbo charger. A: if you feel a small vibration in your gas pedal plus the noise you said, it should be the wheel bearing, has to be changed (cost 50)
Do you always have this noise we you start the engine? Have you don any change of oil last time?
Depending on where the sound is coming from, it may be your fuel pump. Sometimes they are noisy.