starting tuesday night i began to notice a squealing/whining sound while i would hit the breaks so I assumed there was a problem with my brakes (even though i have new pads and had the rotors cut less than 3k miles ago). The sound has persisted since then at about the same volume and at the same time. Today while driving it was considerably louder and persisted while my car was at a complete stop (ie: stoplights) and in park. I did a walk around of the car and nothing could be heard from the outside (because i then thought it might be a belt problem, even though all the belts were replaced at the dealer 4k miles ago). When i got back in the car, the sound was there, and it sounded like it was coming from the rear of the car.

I then went to fill up my tank because i was pretty low on gas---the gas gauge read empty, however its always about 1/4 too low...i put like 10.6 gallons in the car at the gas station.

IMMEDIATELY upon starting the car after filling it up the sound was gone. It was no longer there while breaking, driving, stopped, or anything. This leads me to believe its something with the fuel pump or gas tank or something. Is this a normal thing when the tank gets lower? What could it be? is it a problem?

 

Possibly the tank pressure control valve, EVAP canister/lines, fuel cap, or aliens. Well, maybe not so much that last one...