Audi A4 B6 Fuel Pump

[Hakka]

Maybe someone here can help me out since the 4 ring variety is so similar to VW. It sounds like my fuel pump is headed out on my 03 A4 B6 Avant. 1,8T manual trans quattro. I understand the fuel pump is under the back seat and am staring at it, but what is under the driver's side rear seat? It looks like another fuel pump situation and that is actually what is making the most noise on this car. Some sort of sender?

[ps2375]

The panel screwed to the metal is actually an access panel. The pump is inside the fuel tank and is part of the fuel level sender. Pull the panel and see what you are looking at.

[Hakka]

Feeling pretty dumb right now. What is this thing? A 2nd fuel pump? This is giving off harmonic sounds like a dying fuel pump does.

[ps2375]

I believe so, since you did say it was a quattro, the tank is a saddle tank (I believe), so another pump is needed. I don't know if it is a transfer pump or another fuel pump to the motor. Look it up in a Bently or online parts.

[Hakka]

Got no Bently and nothing online seems to help me out

[Butcher]

Saddle tanks need two fuel pumps to keep the main fuel pump side full of gas. If not, the other side could be at a 1/4 tank and the pump side would be empty. They also need to have two fuel level sensors so they can accurately measure the amount of fuel you have.

I do not know any manufacturer that uses an electric fuel pump to transfer the fuel to the pump side of the tank. All of them use a suction type pump. A lot like how a carburetor sucks fuel into the manifold. So you really only have one fuel pump. I have never seen a suction pump fail unless some monkey was screwing with the fuel lines.

The reason for two inspections covers is so you can have access to both fuel level sensors.

Whatever you do, do not take the covers off unless the gas level is less than 3/4. Matter of fact, the lower the better. I like to see the low gas light on.

No matter how bad you think you got it, there are plenty of PZEV vehicles that have no access to the fuel level sensors, pump, or fuel filter. If you ever have a problem with them, you need to buy a fuel tank. I know of a few cars that were totaled because of that.

[TDCTDI]

[Hakka]

Makes sense and I appreciate the help from all to this point!

Both sides seem to be making more noise than usual but it is that drivers side that seems to make more noise. Maybe the fuel pump is failing and that driver's side "xfer" pump is having to work overtime?

This is the only part I seem to find for the car in searching "fuel pump"
https://www.ecstuning.com/b-vdo-parts/fuel-pump-assembly/8e0906087p~vdo/

[Butcher]

I swear this is true with Mercedes. It was common that the pump failed at the gas station. Why? I have no clue. but it was always a big mess when replacing them. How do you drain the tank? Just turn on the pump. Oh yeah, it's dead and there is no drain.

[Hakka]

Quite late, but I have always hated when someone gets something figured out then the fix is never posted. Forums across the internet have slowed down, which is a shame. The info here is priceless!

The primary fuel pump was giving up causing the secondary to have to work too hard, or at least that is my theory. I swapped out both fuel pumps, starting with the main, and the system was happiest with both replaced..

I should add; go with quality pumps. The knockoff stuff is not worth your time or money. They just do not fit right. I got this done without the special service tool, but if I were to be in there often I would absolutely buy one. I destroyed the original pumps getting them out. That job is a pain and a lot of gasoline contact but beer helps.

Picture because only text is boring.

[obieoberstar]

late to the party, but here goes.

the fuel pump is on the Passenger side of the fuel tank, as well as a fuel level sender. the Driver side has a fuel level sender only. these models use a 'suction jet pump' to draw fuel from the Driver side over to the Passenger side so the electric pump can get it to the engine.