Fuel Gauge Sender

[Sidspud]

How easy is it to change the fuel gauge sender in an Avant?
Am I right in thinking I will need P/N 8A0 919 051 C?
Are they expensive?

Symptoms are whenever the fuel gauge goes under half a tank, it behaves erratically. One minute I'll have half a tank and a range of 150 miles, the next I'll be in the red and the Autocheck is beeping at me. 2 miles later and I've a quarter of a tank again! Its driving me nuts!

[s2avant]

Mine does things like that. Every now and then the gauge will drop to the bottom and the autocheck will go off. When you switch off the ignition it goes up to three quarters. Give it a couple of hours and it's back to normal.

As for your problem. Have a look and see if the sender is in it's brakcet properly. I replaced the sender on mine because it was eratic and found that the tank had been whacked from below and the mounts for the sender are broken.

The mounts are part of the tank so I live with it being a bit dubious under half a tank anyway.

There is also a stabiliser relay to control how the gauge moves. I assume it's there to make up for the fact that the tank straddles the rear diff and fuel level is only measured on one side of it. On new quattros they use two or three gauge senders to work out how much fuel there is.

Ben

[Sidspud]

OK - I'm stumped. I tried changing the sender tonight, but gave up when faced with this....



I hope I'm right with the three connections. The sender plug has 4 wires whereas the replacement sender that I have has only two....
4 wires

my sender


ETKA shows item 2 with no part number - does anyone know what it is?

[Doug_RS2]

Looks very similar to a Mk2 golf - you have to hammer and chisel that plastic thing anti clockwise and then you can turn it by hand - is that where the fuel pump lives on the avant? It will have a couple of electrical connections for the fuel pump as well inside the tank.

It looks totally different to the coupe.

[Sidspud]

So once I get the black plastic ring off, should it all just lift out?

Will I be left staring into the tank if that comes out? Its just that there is a lot of crud lying up in there. Remnants of my trip through the forest in search of rally cars. I don't want it falling into the petrol tank.

[Doug_RS2]

I would hoover all the rubbish out first. Take the black ring off and you should be able to lift everything out - making sure not to bend or break anything.

[Stick Insect]

OK - I'm stumped. I tried changing the sender tonight, but gave up when faced with this....



I hope I'm right with the three connections. The sender plug has 4 wires whereas the replacement sender that I have has only two....
4 wires

Hi Kenny, the connection marked power is fuel out, the other pipe is fuel return from pressure regulater. There are four connections on the connecter as there are 2 for the pump and two for the sender.

As Doug rightly suggested hoovering it off or at worst giving it a blow off with a garage airline. lobbing a bucket of soapy water on it would probabably help.

once clean (er) and dry, spray WD40 around the black ring, this is the lock ring/nut. This is undone by using a broad screwdriver and belting it to undo...

lifting the whole lot out is a bit of a struggle, it's best done with a low or empty tank. Be prepared to flick fuel all over the place!

Hope all goes well.

David

[Sidspud]

Thanks guys. I will attack this later this afternoon (if it stays dry). It'll either go smoothly and everything will be fine, or else I'll die in a horrible spark induced fireball type of death.

Wish me luck!

[Stick Insect]

Thanks guys. I will attack this later this afternoon (if it stays dry). It'll either go smoothly and everything will be fine, or else I'll die in a horrible spark induced fireball type of death.

Wish me luck!

Due to work being extremely busy it must have taken me just short of 3 hours working on that response, you and doug posted in the time I was trying to work on my reply!

I would make sure that you have turned the supply off to the pump as the terminals aren't insulated and they sit in petrol!

If you are going to die in a fireball make sure that you have lots of sausages and burgers so your neighbours can have a barbecue!

David

[S2 Ant]

In true Haynes manual style....

Step 1... Disconnect the Battery..........
....
....
....
....
....

Refitting is reverse of removal


Does look similar to some of my old dubs and that was a PITA to get undone!! Used screwdriver and hammer and also tried swan neck pliers.... eventually got the ****er undone, was on damn tight tho (for obvious reasons!)

Just dont go blowing ya self up!

[Sidspud]

Woo Hoo - I survived!

Not only that, but I fixed it! Here's a quick How-To.....

1. Disconnect the battery
2. Remove the top cover in the far right corner of the boot (3 screws)
3. Undo clamp No.1 and prise the hose off
4. Undo banjo bolt No.2 using a 17mm socket (BEWARE - petrol will spray about for a second or two, so have an old towel handy!)
5. Disconnect connector No.3
6. Batter No.4 anticlockwise with a hammer and screwdriver until it screws off



There is a connector on the underside of the top section that can also be disconnected. It is possible to access the tank without doing this, but it is much easier with it disconnected. You should then see something like this....



The sender is the new white bit I'd just fitted on the centre right of the pic. The fuel pump is in the middle of all that brown plastic. Both connect to the underside of the top part as David suggested. The sender just clips in and out.
I replaced the seal whilst refitting. Put it in the hole and then put the cap on rather than my first attemp of fitting it on the cap and then trying to get the whole thing back into the hole!
Put it all back together and Bob's your mothers brother!

[Sidspud]

And here is the fault...

When the tank was full the wires connected.....


But when it got low, the wire lost touch and gave an empty reading!


I'm well chuffed that I managed to fix this on my own and also that I managed to diagnose the fault! Many thanks to all who offered halp and advice.

[stragenmitsuko]

Pity you bought a new sender .
All you needed to was replace that broken wire .
This kind of problem isn't uncommon amonst
vag cars .

Pat

[Stick Insect]

Pity you bought a new sender .
All you needed to was replace that broken wire .
This kind of problem isn't uncommon amonst
vag cars .

Pat

Pat, you should know by now that when working on cars if you have the parts you don't need them!

Well Done Kenny, Engine re-build next then?

David

[Sidspud]

Well Done Kenny, Engine re-build next then?

Erm...no. But I'm off to try and replace an ABS sensor now! It doesn't work anyway, so if I bodge it, I'm not losing anything!