Xantia fuel level indecator. Removal and cleaning?

[TehAgent]

How easy is it to remove the fuel level indicator from the tank and clean it up, as mine really does give false readings, i can put £10 in the car and the light never goes out, always says its empty.

I put £15 worth of diesel in the old girl two days ago, when i turned the ignition at the pump to pull out of the garage, it was above the red light mark, but about 3 miles into my journey it dropped back down to almost showing nothing in the tank (just a tiny bit of white line)

The manual states that when the fuel light comes on, there should be 8 liters left in the tank, well 15 and 10 pounds worth of diesel is a lot more than 8 liters,

Yet my dashboard indicator never seems to show me the correct amount, I'm thinking its something to do with the level reader in the tank and that it might be grimed up or something.

I do know that if i remove it i will have to replace the seals with new ones, just need to know if its a fairly easy job before i commit my self to taking the back seats out to get at it.

[AndersDK]

Your tank sender unit will not be gunked up. Immersed in fuel it will always be kept as clean as the fuel.
Still it might be a good idea working your way down to the sender, as the most likely problem lies within the cable or connector to the sender unit.

In rare cases the sender unit slider may have worn a dead track in the resistor element causing the false readings.

Check that the cable to the unit has one wire with a good earth. Also the gauge should read full tank with disconnected unit, read empty (+ lamp on) with the sender cable earthed.
You should not find any live wire on the cable, so wont harm anything if you mess about with probing.

[CitroJim]

Ian,

Was this problem evident before the acid spill? It may well be connected.

I have a feeling the level light and gauge are on separate circuits but cannot confirm because I'm nowhere near my BoL or my TD (which has gone to Norfolk for the week) and the Activa has a totally different set-up.

I can have a look in my BoL later if you need me to and then I can identify the right wires.

[jeremy]

Your fuel gauge and its other bits are not precision instruments and give approximate indications of the fuel present in the case of the gauge and start flashing to remind you that the fuel is low in the case of the warning light.

Just imagine the job it has to do. The fuel tank probably is about 2ft 6 in square (750mm) and 250 mm (10 inch) tall. It probably holds about 14.5 gallons (66 litres) which means that 1 litre will raise the level by 250 / 66 mm (3.75 mm or 3/16 inch.) On top of this the fuel sloshes around and the gauge mechanism is designed to damp these oscillations out.

Our ZX is supposed to hold about 12 gallons. I always fill it right up but the max I can ever get in it is 8 gallons - even with the light flashing on. I still achive a range of between 350 and 400 miles - so it isn't worth worrying about the 4 gallons of unused fuel in the tank.

[Peter.N.]

The gauge on one of my XMs gives intermittent readings, having checked the sender unit and continuity of the cable, (I get a reading of about 160 ohms both across the sender and the leads where they go into the instrument panel) I have come to the conclusion theat the gauge or associated PCB is faulty. There is only one pair of wires from the sender (signal and earth) so it would appear that the low warning light and gauge work from the same input.

[TehAgent]

Your fuel gauge and its other bits are not precision instruments and give approximate indications of the fuel present in the case of the gauge and start flashing to remind you that the fuel is low in the case of the warning light.

Just imagine the job it has to do. The fuel tank probably is about 2ft 6 in square (750mm) and 250 mm (10 inch) tall. It probably holds about 14.5 gallons (66 litres) which means that 1 litre will raise the level by 250 / 66 mm (3.75 mm or 3/16 inch.) On top of this the fuel sloshes around and the gauge mechanism is designed to damp these oscillations out.

Our ZX is supposed to hold about 12 gallons. I always fill it right up but the max I can ever get in it is 8 gallons - even with the light flashing on. I still achive a range of between 350 and 400 miles - so it isn't worth worrying about the 4 gallons of unused fuel in the tank.

Yep i understand what your saying, but the problem is, even if i fill the tank with £20 worth of diesel it hardly moves above the Low fuel mark, that indicates that i have only 8 liters left in the tank.

When in the car park (flat surface) the car will read zero on the fuel, until i start moving, then it raises about 3 mm off the bottom most marking on the fuel level indicator on the dash, then about a mile into my journey, it will read nothing again, yet i can get 160 plus miles out of it, so its definitely a fault somewhere along the line or with the fuel probe thingy in the tank.

Jim,

Its been like this since i had the car. so any information you can dig up on it, please let me know. its been more noticeable this month as we have had little money to put into the tank, as its been spent mainly on getting it sorted for its MOT.

[elma]

Try hitting the dashboard after you fill up. Sounds silly but my rev counter used to stick. One day I got angry and thumped it. Always worked since.

If you can get it to read about right with how much fuel you've just oput in thats as good as it will get. I have a xantia and drive 2 others. All of them under estimate the fuel by quite a bit after the car gets moving. They only read around right when on the motorway. They do, however, read about right after filling up.

[CitroJim]

Try hitting the dashboard after you fill up. Sounds silly but my rev counter used to stick. One day I got angry and thumped it. Always worked since.

Works for me on the very rare occasions my temperature gauge plays up Seriously, it is worth doing.

Ian, the circuit is as follows according to the BoL:

Ignition switched +12V is picked up by the gauge via F2 on wire C12G.

The gauge and sender are both earthed at a muliple earth point (under the dash somewhere I guess) via wires M02D (gauge) and M432 (sender)

I've just realised, all earth wire numbers begin with an M for Merde I guess

The sender signal goes to the gauge via wire 432. It is this wire you need to earth to see the gauge read zero or leave open to read full.

The light also works from this wire so when wire 432 is disconnected it should be off. It works by finding an earth through the sender when it is at its low resistance end (i.e. nearly empty tank).

This'll prove if it is the gauge or the sender.

The sender is easy to swap

[lolingram]

English please Jim (in jest I should add...) Could well be right.

I've just realised, all earth wire numbers begin with an M for Merde I guess