2.5 tdi Lift Pump Issues

[rizla3066]

Hello, i am having issues with the fuel pump located in the tank.

I have been through the threads on here and others, Hooked a wire from the battery to fuse 28 and the pump works. So next i have pulled relay 373 out and that does not seem to be working, however i am unsure if the relay is not working or if there is no power to the relay.

I have pulled the top off the relay and inserted it back in to its holder, now using a multimeter i have checked fuse 28 with the car started and no voltage through it at all even if i operate the relay by hand.

Does anyone have any ideas? What controls the relay?

Thanks

[Crasher]

Quattro and AKE? Year?

If you are looking for a head of fuel at the filter from the in tank pump, you are going to be disappointed. The in pump tank is described as a pre supply pump and all it does is to provide a full swirl pot of fuel in the tank for the VP44 to suck from, it does not provide fuel to the fuel filter.

[rizla3066]

Quattro and AKE? Year?

If you are looking for a head of fuel at the filter from the in tank pump, you are going to be disappointed. The in pump tank is described as a pre supply pump and all it does is to provide a full swirl pot of fuel in the tank for the VP44 to suck from, it does not provide fuel to the fuel filter.

Thanks for the reply

No its a multitronic BDG.

The pump does infact send fuel to the filter, i tested with the return valve disconnected and powering the pump through fuse 28. This pumped fuel to the filter and made it overflow.

The issue im having is that the is no power to fuse 28 to power the pump, from what i have read it is powered from relay 373 from under the drivers foot well.

There is no power it the fuse even if operate the relay manually?

Thanks

[Crasher]

Which year and engine type code?

[rizla3066]

Which year and engine type code?

Its a 2004, engine code BDG

Looking on elsawin i dont think its relay 373 but 395 located under the ECU, either way no power to fuse 28 when started

[Crasher]

It was the pre 2003 model year where the VP44 had to do all the work. The fuel pump relay is fed by the ECU relay on the same circuit and there is a welded join in the harness where the 2.5-mm red/yellow from the ECU relay splits into 3 2.5-mm wires and then the fuel pump feed goes into a 17 socket red connector block in the engine bay electronics box before carrying on to the fuel pump relay now as a 1.5-mm red/yellow and goes under the dash to the fuel pump relay position 6 to sockets 6 and 2 of the ECU relay holder. Check the ECU power feed at pins 1 and 2 of the ECU if there is no power at the red/yellow to socket 2 of the fuel pump relay holder. The power from the relay then goes to as a green/red to fuse 28 in the dash side fuse panel and then from the fuse to the fuel pump as a yellow wire.

[rizla3066]

It was the pre 2003 model year where the VP44 had to do all the work. The fuel pump relay is fed by the ECU relay on the same circuit and there is a welded join in the harness where the 2.5-mm red/yellow from the ECU relay splits into 3 2.5-mm wires and then the fuel pump feed goes into a 17 socket red connector block in the engine bay electronics box before carrying on to the fuel pump relay now as a 1.5-mm red/yellow and goes under the dash to the fuel pump relay position 6 to sockets 6 and 2 of the ECU relay holder. Check the ECU power feed at pins 1 and 2 of the ECU if there is no power at the red/yellow to socket 2 of the fuel pump relay holder. The power from the relay then goes to as a green/red to fuse 28 in the dash side fuse panel and then from the fuse to the fuel pump as a yellow wire.

Problem seems to be the 395 relay, one on order from audi. The relay had been wet once upon a time, i had cleaned the ECU compartment out a few months ago and i remember the 395 relay was a bit rusty at the time but cleaned it up along with the wiring but obviously it hadn't worked. Thinking about it i have had this issue with air in the fuel line since about that time. I put it down to a bad seal on the filter and ordered a new return valve and filter. Fitted that and all seemed good, on tick over it would be ok with no air in the line but after a while i noticed that after revving the car for a while the filter would partially empty and drag air in again, but on tick over again all looked good.

I was under the impression the was no lift pump on this model but a bit of research yesterday confirmed there was, and after bypassing the relay and powering the pump from battery the problem of air in the line seems to be no more. Will update tomorrow when i have the relay, thanks mate