Katee34

XF Fuel Gauge Reading Low

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I have a 3.0D XF 2010 with which I am generally well pleased however:

I have had the disappearing fuel gauge problem, diagnosed by a non dealer jaguar specialist as down to faulty connections inside the tank.  The connector was removed and the wires crimped eliminating the original problem – however when the sender unit was replaced in the tank the fuel gauge registered less than half full when I had filled the tank to the brim and yet the range indicated only 220 miles – ie circa less than  half what I would have expected. The “range” figure  now decreases with mileage at about the right rate and mpg figures are still as expected .  What is the new problem due to?

The mechanic had not come across a similar situation before and even removed and refitted the unit.

As the fuel level measurement had been OK before the repair, I am reluctant to have the sender replaced if there might be another cause. 

Is it necessary to reset the computer; is it due to damage or some electrical wiring issue; or will the system relearn and correct by itself?

I would be grateful to hear from any fuel system experts out there.

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Hi

If it was working ok before the sender repair, then its got to be the sender or wiring

If the sender was wired incorrect, then it would read wrong

I'd take it back and get it checked, where the repair was done

on some cars, when fitting new senders, they need recalibrating, but if your has the original one, just had the connector removed it should read the same

I'm wondering if they got the wires mixed up when the removed the connector and fitted the crimps, sometimes the wires are all the same color and these could easily be mixed up and that would give the symptoms you mention

cheers

Joe

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I wasn't aware you could purchase just the sender unit? As genuine Jaguar XF 3.0D replacements come with the pump attached at a cost of £300+. So doubtful a new sender was fitted unless aftermarket are now available? The old sender can be separated from the pump while still in the tank if the diesel is low by removing the wires to it inside the tank and sliding it off the pump (It's not so easy if removing both pump and sender as the flow and return pipes inside the tank can be a problem removing and refitting to the the pipes. You could try putting your hand into the tank and lifting the float to see if the gauge reading alters? As for re crimping  the wires on the multi connector these are held in a plastic block and being thin wires can't be removed without damage, The usual trick is with a small blade down the inside of the block to close the gaps on the connectors and spray with an electrical anti seize.

If want to give ago yourself it's not a difficult job if the diesel in the tank is low, Just a bit smelly. Lift the back seat swab There's 2 catches one under the middle of each side where any passengers sit To save the fiddly job of removing the rear seat belts,Lift the back seat as high as you can and place props under to support and make sure the props are secure! On the off side rear door pull up and off the plastic cill kick trim that holds the carpet in place. Then fold the carpet back. Your see a large round black plastic plug, Carefully side something down the edge of the plug and once you can get a finger under work your way around and remove. Under the plug your see the pump and sender top with the wire connector you said was re crimped, Release the connector clips and pull off. To gain access to the inside of the tank with a bunt instrument tap the metal sealing ring until you can remove it. Remove the pipes on the outside of the pump. And gently lift the pump until you can get you hand in side the tank, The pipes inside the tank are corrugated clear ones so care not to kink.

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Ah just reread your problem. There would be no need for whoever was crimping the wires? To remove the sender unit as the ones inside the tank from either the pump or sender unit to the underside fitting never give problems.Its the ones on the tank outside that gives problems due to road dust and dirt being thrown up onto.If only now reading half a tank when full it would more and likely the winding on the actual sender unit it's self being either worn through or faulty. A very common fault on the 09-10 year models which I have on good information was caused by jaguar using units supplied by an eastern block country.

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Thank you to both of you who posted helpful replies.

Please excuse my ignorance of this web site ,but I tried to reply to you and it just got lost and I will have to do it again.

My origianal entry is now shown greyed out - what does this mean please - I cannot find any advice on the use of the web site

I chose to use the members only section - was this correct?

Your help before I try to repost would be appreciated

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Just to clarify the history so that the evidence is clearer, 

I too first understood the problem of the disappearing fuel gauge was associated  with the connector on the top of the unit immediately under the black plastic cover under the rear seat.  Before going to the garage I had inspected this ,and found condensation as has been pointed out. I wiped this away, released and disconnected the connector to inspect it.  The contact metal was bright and clean. I tightened up the connector blades to ensure a tight fit on the spade ends, worked the connector up and down and reconnected.- but with no effect on the disappeared fuel gauge.

It was at this point that I went to my garage and was informed that the problem was not so much the exterior connector but usually associated with the connections inside the tank –under the fuel of all crazy places!

I do not know/have not seen what is inside the tank so the following is only what I have been told.

The mechanic removed the “sender unit”  from the tank and then inside the tank removed the connector and crimped the connections.  He replaced the sender unit – ie the original .  He was puzzled that the now restored fuel gauge read low and re examined the unit to see if there was any damage or sticking of the float- but there was none apparent. I decided to try the car to see if there might be any self healing and to return if not – still early days yet .

1  I am particularly interested in the comment and  possibility that the problem might be caused by incorrect connections on the crimped leads.  How many leads are there  and hence what scope for error?  If the sender signals are digital as I believe they may be then is polarity an issue.

2  I have read elsewhere in another post that there is a magnet on the side of the pump/sender unit which can get displaced. Do you know anything of this as it was not known to my mechanic for this model?

 

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Clearly there is at least one fault but I wondered if the additional information below gave any more clues to the possible causes. As above, after the repair, I started with a full tank and gauge reading just under half full , Range “220m”. Since then I have done 220 m and still have a range of 185m ! Odometer seems to be accurate as are mpg readings. The gauge has slowly descended from just under half to just over quarter and made its way back to just under half!

Additionally a firm press on the accelerator sometimes produces the expected punch of acceleration but at other times just a long delay before acceleration or even nothing – as if there was air in the fuel line.  Progressive acceleration and smooth driving are as normal.  Any further ideas guys?

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Hi

don't know if this helps

but you can put your dash in a diagnostic mode and read the data coming from the fuel level gauge and you should be able to find out what up with it

I have attached the relevant pages and the complete workshop manual, page 2456 is where it starts

cheers

Joe

These are just google off the tinternet

manual 2008XFWorkshopManual.pdf

ScreenShot203.jpg

your looking at fuel gauge operation and fuel gauge reading

and when in diagnostic mode its test 21 for the fuel gauge

ScreenShot201.jpg

ScreenShot204.jpg

ScreenShot206.jpg

 

 

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Thanks Joe for the references. For any who might be interested ............ After a few fill ups it was clear that although the gauge now read something rather than nothing ,it was still behaving oddly- wandering up and down within a small range even though fuel ranged from tank full to mostly used.  Mechanic took it back to have another go or replace sender.  He found a dry joint on the sender unit and fixed that. Since then it appears to be OK though I will not be fully confident until I have used several more tankfuls.

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For any who may have been following this one I am pleased to say that the mechanic's perseverance and interest in solving the problem seem to have paid off.  Having found a dry joint on the original sender unit and corrected it the gauge appears to have worked as it should - having now done several thousand miles and filled up a  few times.  Lets hope that remains the case.Thanks to all who forwarded useful information and ideas.

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Hi, I have the issue where my fuel gauge is empty, although I have filled it up a number of times - to the point where its full.

This happened last week when i let the tank run near empty.

The revs on the car dip every 5 seconds, and after 60 seconds the car turns off.

Im assuming I have the issue where the fuel gauge connector is at fault?

Iv lifted the rear seats and the black access cap and see the connector with many cables going into it - I cant get the connector out to clean it - how do i do this?

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Hi Minesh

I have not been on the forum for a while so have only  just seen your post.  I hope that you have by now found an answer.  If not, please be aware that the problem I experienced proved to be connections inside the tank and under the fuel!  If you are not too sure about dealing with the external connectors ,it might be best to find a good independent jag specialist to try looking inside the tank.  My guy is very experienced and even he said it was not a job for the faint hearted.  He had to work virtually blind with his arm deep in diesel fuel, before he could determine the problem. Although I have done quite a few types of repair I am pleased I left this one to him!

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I've just read this post - very interesting. Ever since I bought my 2010 XF the fuel gauge reading and range have differed from the amount of fuel put into the tank. Last week the Low Fuel message popped up, even though I knew I had over 180 miles to go. I went through the system settings on the centre console screen and it was registering 189 miles; yet the small screen over the steering wheel is still showing Low Fuel Level. Are these two read-outs not linked?

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Dear All

Jag XF S portfolio 59 plate diesel

Fuel level shows ZERO and an alert is shown saying as much.

Continued driving as i did after 100 miles car seemed to have a slight engine fault for about 30 miles ,on and off, Then just after i left home one day the engine cut out completely.Found out the car is very heavy on the steering wheel without engine going.Engine restarted after 10 mins and i was able to limp home 500 yds.

I now understand that the above is a software preventive measure to keep 5 litres of diesel in system to prevent HP diesel running empty.

NOW

The S type only has one access point into the fuel tank .I tried the wire repair inside the tank and that worked for about 6 months then it appeared again and the wire repair  failed even after several attempts.THEN for some reason i rubbed a magnet up and down several times over the level sensor (At the pivot point of the float arm) and it worked .This repair has lasted 9 months till last week when it failed again BUT the above again worked .

The float level is a series of metal  fingers that are moved by a magnet attached to the float arm and i suppose that some of them can get caught up over time .

I am not a car mechanic just an average DIYer ,Magnet repair takes about 30 mins

Hope this helps

 

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