start off saying i have a 88 transam GTA auto, about a month ago a humming noise occured. only thing i have done to the car was get the transmission rebuilt about a year ago, only my put 3,000 miles on it so far. this kinda has me stummped so this is how it goes. after letting my car warm up then getting in it to go, a humming noise starts, it sounds like it is coming from roughly about where the passager puts there feet, now when im driving and give it gas it it goes away even the littles touch of the pedal it goes away. If im not giving it gas no matter what speed it hums, hums all the way intill i fully stop then goes away. pretty much as long as the car is moving with no gas it hums, have tried just coasting in neutral, put muffler tape around my exhaust where the clamps hold the cat, im assuming its something todo with air getting in or leaving somewere. I know i just wrote a book but any advice would help me a ton! thanks a billion

 

Sounds like your fuel pump

 

cant be the fuel pump you can hear it from start and while driving, this is about 10x as loud as the fuel pump

 

Exhaust hanger loose, suspension worn, tires good?

 

Pretty vague description...

Cat somehow? Or maybe wheel bearing?

 

sorry forgot to mention, new suspenison, tires, all a year ago, could a exhaust hanger make humming noise with no gas then go away with gas then back and forth kinda like (on,off,on,off gas,no gas, gas, no gas)

 

Engine harmonics can transfer noises into the cabin. If the exhaust contacts the body then its a ppossibility.
Forgot but TreeFiddy can be onto it too.
Check the play in the wheel with the front off the ground & safely supported-- see if there is slop moving it up & down.

Just trying to start with the easiest stuff, which is my limit...

(edit)
wait-- I think that wheel check is for ball jonts..??..

 

so i got under the car the air tube going to the cat has been cut and a hose is in its place to reconnect it, i took the hose off and started it up, is the air coming fro the tube suppose to be pushing air or sucking air?

 

Had the same issue was the pinion bearings in the rearend.
As said harmonics can move around throwing you off.

 

Air injection pipe is touching something, possibly the body, but more likely touching the cat somewhere. Just feel pipe from the engine to the cat, and somewhere it will be too close. The metal pipe is very soft, and it's easy to bend away from any place it's too close.