Okay so a few weeks ago I drove about 80 miles from my work to a friends house and when I parked my car, a 2005 audi A4 1.8l turbo with quattro, I noticed an annoying humming noise comming from the rear of the vehicle. The next morning, I was leaving to go out and when i went to start my car, it was making the same noise. I turned the engine off and just turned on the electrical portion of the car and the car made a high pitched noise. After talking to a few mechanics, they all immediately said they thought it was my fuel pump. I had the pump replaced, but the noise was still present. Right after having it "fixed" the noise started when I started up, but dulled when the car was idling. When I would accelerate the vehicle, the noise would become load again. The mechanic said that it may take a few days to wear the bearings in on it if they are still sharp. Now almost a week later, the noise has changed. Now, the noise is always present in different degrees. If I am idling, it can be extremely loud and lessens when the car is accelerated. Also, the sounds seems to be less intense when the car is warmed (I live in New England) for several minutes. I can sometimes hear the electrical system trying to do something because the noise will stop for a briefy period of 3 or 4 seconds and then start. Could it still be the fuel pump but the new one was defective? Was it never the fuel pump? The noise is really high pitched when the car is electrically turned on and when it is driven from a cold start (like when I leave work). Also, the car is realatively new with less than 60,000 miles on it. Please help me out! Thank you to all who has advice.

 

i may be wrong, but could it possibly be the fuel pressure regulator?

 

All I know is that is driving my crazy. I will say though over the last day or so, the noise had dulled altogether, but before when it had just been fixed, the noise was aporadic. Now it is constant, sometimes umbearable and embarrasing. I know it is coming from the rear of the car and I am pretty sure from the passenger side which coincides with a fuel system component failure. I just dont know if I spent money on a new fuel pump when the original one worked fine and it was a different problem. What exactly does the fuel pressure regulator do? I trying to determine what parts in the fuel system do exactky what and if they are linked to the electrical system that would cause that noise. Thanks.

 

Clogged fuel filter causing the fuel pump to work harder/wear out quickly?

 

well im using logic here so correct me if im wrong. im pretty sure the fuel pressure regulator regulates the flow of fuel coming through the pump at a given time. definitely an electrical component.

 

I've never seen an electric fuel pressure regulator, and all of the ones I've seen are in the engine bay. I don't know where they are on our cars.

It's also possible that the replacement pump is/was bad. I would get under the car and listen to try to pinpoint the noise.

 

The mechanic, who replaced the first one and I have found to be extremely reliable, believes that the pump replace could definitely be defective and has offered to replace the defective part for free with free labor. I actually did get under the car a few days and it is definitely coming from the back of the car and I almost positive it more to the right. When its really load, it can be difficult to pinpoint. But once the car has been running and the noise is lower, it is without a doubt coming from the fuel area. I am not sure about the filter at all, so I will have to check.

For the fuel pressure regulator, Im not sure where its located, but if it is an electrical component and not a mechanical, then would it have coded when the car was diagnosed?

I am also going to ask him about my fuel filter, but I am going to see if i can check it myself. I have heard clogged fuel filters can represent weak or bad pumps.
I thank everyone for they posts. Believe it or not but your really helping me out.

 

Sounds like you have a good mechanic!

 

probably a defective fuel pump but not 100% sure. Changing the fuel filter would be a good idea. As a side note you do not have a fuel pressure regulator. The fuel pressure on the B6 non-return fuel system is maintained by a spring loaded bypass built into the fuel filter.

 

You should replace the fuel filter. It is located by the fuel tank on the right side. Your mechanic only fixed half of the problem. He need to replace the fuel filter too. Audi does have a TSB about this problem.