Humming noise inside car...

[2mAn]

Car is an 84 318 with an M20 swapped in. 87 iS harness was used to power motor. Not sure of the history of the rest of the wiring.

Car has a humming sound when its on, almost like the fuel pump is about to run dry, but it does this no matter whats going on. im not sure if the noise could be related to the shitty stereo wiring because it has the whine as well. However, whether the radio is on or not it still makes the noise.

Any thoughts on what I should check out?

[Quadrajet]

I'm assuming it only does this when the Igniton switch is in the "on" position. I wonder if it still has the external fuel pump? Or an amp somewhere?

[2mAn]

I drove home without the stereo on and it was there most of the time, but it did go away at times.

[Pocket Chant]

I had that problem when the ground to my stereo was bad, though it went away when it was fully off.

Try pulling it out and wiggling the wires.