Whenever I drive my RS for a while 5+ miles, a terrible humming/screeching noise comes from the rear of the car. Sometimes it does, sometimes it doesn't. It also usually shuts off with the car, but sometimes doesn't for a while. Once when it did it i crawled under my car and tried to find out what it was.

I ruled out:
Hatch Motor
Speakers
Rear End

My best guess is that it's the fuel pump, but heres the kicker, its new with <2000 miles on it. So could it be a simple relay or something? My TPS is also acting up if that helps.

Thanks for any help i get

 

Bump. So i figured out that it is the fuel pump.
And it never shuts off, so it'll just randomly come on for an hour when the car is off.
What could it be?

 

obviously a wiring problem.

 

Before tracing wires, test the fuel pump relay. It could be shorted internally or the connecter could be fried like mine was.

 

The oil pressure sending unit above the oil filter will go bad and cause the fuel pump to run even when the car is off and the key is out. Unplug that, and go a day and see if it still comes on, then I'd say it's possibly the relay.

 

That relay is probably wired in a 'normally open' state. That means that unless you give it power, there is no connection. If it's randomly turning on, I'd look for problems along your IGN wire on the relay.