A2 1.6FSi - fuel gauge works in reverse after the new fuel pump (in tank) had been fitted

gromand

Member
Hi there,

does anyone know anything how to resolve the problem detailed above?

The original fuel pump gave up 2 weeks ago. Since a garage was not 100% sure it was the fuel pump they fitted the
cheapest one from Euro Car Parts.
The car became sluggish on the 1 and 2 gears AND, what is more, the fuel gauge started to work in reverse. The more
I drove, the more the fuel gauge arm moved to the FULL tank.

They advised to fill a tank full and to see what happens. I filled the tank and the fuel gauge arm pointed on 11:30am if
you imagine it at the fuel gauge as if it is a clock's face.

They returned the pump to Euro Car parts and brought a Pittsburg one (the most expensive the ECP had) from them.

The car became nippy on the 1 and the 2nd gears as before yet the fuel gauge still works in reverse.

The garage told to bring the car again.
Yet, from their eyes I see that they are baffled with the problem and do not really know what to do.

May be I should just tell them to fit a genuine Audi part? I am going to keep my A2 as long as practically possible anyway
thus it is worth to fit the new genuine parts instead of the failed ones.

The problem is - what to do if the fuel gauge still works in reverse even with the genuine Audi fuel pump...
 

Robin_Cox

Member
Drive it like you stole it and sell the petrol you're producing to A2oc members at 50p / litre... :)

Being serious for a minute - could this be something as stupid as the connector being attached in reverse (I assume that this shouldn't be possible), or does the measuring device attach in two possible orientations - i.e. it has been re-attached in the wrong direction?
 

gromand

Member
Drive it like you stole it and sell the petrol you're producing to A2oc members at 50p / litre... :)

Being serious for a minute - could this be something as stupid as the connector being attached in reverse (I assume that this shouldn't be possible), or does the measuring device attach in two possible orientations - i.e. it has been re-attached in the wrong direction?
Well, I thought about reversed connectors
Drive it like you stole it and sell the petrol you're producing to A2oc members at 50p / litre... :)

Being serious for a minute - could this be something as stupid as the connector being attached in reverse (I assume that this shouldn't be possible), or does the measuring device attach in two possible orientations - i.e. it has been re-attached in the wrong direction?
Well, I thought that a mechanic reversed the connectors while fitting the pump. Yet, the MECHANIC, not myself? Besides, it is the second pump already... done the same way then?
 

Catnip64

A2OC Donor
There are different fuel pump/sender units available and if swapped over you will find the gauge is not calibrated correctly and operates in reverse.
The part number of the unit for the 1.6FSI is 8Z0 919 051 C.
Check the part number of the unit that was removed and find the same one, or measure the resistance at the empty/full positions and compare with the replacement.
 

depronman

A2OC Donor
As Catnip indicated, there are different pump/sender units and from 04/2002 the resistance 'logic' of the level sender was reversed.

If they fitted a pre 2002 design pump unit in your later model year car, that would explain the 'full / empty' problem

A2 Cars summarised the 'resistance' changes in this old post - https://www.a2oc.net/community/index.php?threads/fuel-gauge-swap.19558/post-149511

Cheers Spike
been there and got the tee shirt :)
Only Audi could do something like this mid model
 

gromand

Member
Here is the update on the problem that was eventually resolved.

First of all, thank you all for the answers.

So, the fitted pump was a Pierburg one bought from Euro car parts. They are OEM manufactures so have some peace of mind.
Yet, on the hindsight, had I known the problem, I would had to have bought an Audi's fuel pump.

The mechanics compared my broken Audi pump with that Pierburg one. The arms that move when the level of fuel goes down are
very different - although it was not a problem.

I found this:

https://workshop-manuals.com/audi/a...l_supply_system/checking_fuel_gauge_sender_g/

that gives the resistance of the full and empty fuel tank (the very last table of the document). I showed this to the mechanics.

The Pierburg's resistance differed by 3 milliampers or whatever units the resistance is measured.

The problem was that the metal plate along which moves that arm that measures the level of fuel in the tank
showed reversed reading. It was calibrated in such a way that when the actual fuel level becomes lower the resistance
showed the increase of the fuel. No idea why it was like this.

The mechanics in the garage used a sender/sensor unit from my original Audi pump and fitted it to the Pierburg pump.
They did it for free, nothing to say yet, a Pierburg pump is only £80.00 cheaper than an Audi's one from a dealer
I just had to buy an Audi's one from the very beginning.

Taking into consideration that I do not see any car that I want to buy when my A2 is out of the road I have just to
fit the proper new parts instead of the failed ones to keep the car going as long as possible.
 
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