2.5 tdi Lift Pump

[rizla3066]

Hello, today 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

 

[Mike B]

What issues?Can you get a scan?

 

[adamss24]

They rarely fail them lift pumps- i reckon the fault is the main injector pump...

 

[rizla3066]

What issues?Can you get a scan?

No codes, and i wouldent expect any really.

They rarely fail them lift pumps- i reckon the fault is the main injector pump...

Injection pump is fine, just there is no power to the the lift pump in the rear. So the injection pump is doling all the work to get fuel to it, and because of this it is pulling in air. With the lift pump powered up there is no air in the fuel line.

 

[adamss24]

Does it start badly ? Takes long cranking ? The fuel pump only works with engine running, there's a relay in the ecu are which supply power to the pump, they fail from time to time. If the pump is drawing air then the issue does not lie in the lift pump but most likely the fuel filter does not seal the tee piece properly- get a genuine hengst/bosch or mahle fuel filter and new tee piece from local dealer...

 

[rizla3066]

Thanks for the reply.

I had already got a new Hengst filter and new Myle return valve but the issue was still there.

Problem was with the 395 relay, got one from audi this morning. 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.

New relay in and no more air in the line.