Xantia Fuel Gauge a mind of it's own...

[kentc5]

Hello guys,

When I bought my Xantia the fuel gauge was empty... like it could not go any further.... went to fill her up with diesel and found out the tank was full!
I then tapped the dashboard where the fuel gauge is and this brought her back to life ... been working ever since... until 4 days ago.

It now shows empty ... not as low as when I got the car, but no matter how many times I tap her or ... l knock ... doesnt seem to change.

Any fixes or solution to this? I have put in fuel twice since then but it hasnt make any changes....
I also removed the battery for a few hours .. but still made no change.

Cheers
Vasilis.

[kentc5]

OK a quick update, I added 3/4 of diesel fuel additive in the tank and also went and filled up with diesel it is it full up to the brim. Put in 45lts of fuel ... and now the gauge shows the tank is half ... instead of full!

[citroenxm]

It really sounds like the fuel guage "Daughter" board is playing up, which is buried inside the speedo clocks...

you'll need to get the speedo/rev counter unit out, and open it up.. inside roughly behind the speedo is a small curcuit board which controls the level on the dash... its this that converts the sender signal to the guage signal..

Change that... ! I would NOT have thought the sender in the tank is faulty, its a rarer thing to go, but many people blame it first because they havent realised theres a "Middle" bit..

[kentc5]

cool will clean it and check the soldering on it ...

fingers crossed that will sort it out

[citroenxm]

I dont think its a soldering thing, its possibly a Component problem, I on one I had to do, simply swapped the board for another out of another set of clocks...

[kentc5]

will have to look at it once I manage to take the clocks out ...
it is not as simple as I thought it would be and people get on about how bad the citroens are built lol ... it seems very well bolted in to me!! lol

[CitroJim]

Sounds like the age-old MK2 Xantia problem of poor contact between the gauge proper and the circuit board behind. The gauge has four spring 'fingers' that press against pads on the circuit board and muck and a slight loss of temper in the fingers can cause a dodgy connection.

That you once clobbered it and all returned to normal strongly suggests this is the case...

Here's some pictures of an instrument cluster in bits...







Paul, isn't the daughter PCB you mention only applicable to the MK1 instruments... I can't think of a daughter PCB on the MK2 instruments except for the black heat sink that contains a voltage regulator IC. If that goes then it would likely affect all gauges equally I'd have thought...

[kentc5]

Great thanks for the pics .... that will shed some light.
Yes this one I have is one of the last Xantia's I guess being Sept 2000 model.

[kentc5]

Hello Jim,

It is exactly like the one you pictured.
I have opened cleaned the 4 pins behind gauge...
cleaned the contacts on the board as well with PCB and Flux cleaner plus a brush ...
But it did not seem to fix
I might try to apply a bit of solder at the end of pins and contacts on the board see if this remedies the problem

[citroenxm]

Ah Jim, Well Yes, I was reffering to Series One setups, I didn't realise that S2 was different..

[kentc5]

well i applied solder and made sure a contact was there still though the problem is not fixed

[Hell Razor5543]

I wonder if the problem might be down to a clogged sender unit;

http://www.frenchcarforum.co.uk/forum/v ... =3&t=42242" onclick="window.open(this.href);return false;

[kentc5]

I think that might be the problem, tomorrow I was going to open the "under rear seat" black hole cover and see what I can see there.
But I have a full tank of fuel ... more than full

[Hell Razor5543]

Then I would run it for at least 300 miles to drop the fuel level down to at least half empty, so you don't have to get all messy (you and the back seat) cleaning the sender unit.

[kentc5]

a days work's travelling will do that