As they would say across the pond, "dodgy." Yup, that's mine. Sometimes it works sometimes it doesn't. I pulled a working sending unit from a 92 XJ6, it's the same one. I hooked it up to the connections, gauge still didn't work. Anyone else fix theirs? I traced the wires, there really isn't much to it. No fuse or relay that I saw from the wiring diagrams, that go before the gauge.

 

I bought a brand new sender and had it fitted when I had my tank out getting the fuel pump replaced. The gauge does exactly the same weird stuff now as it did with the old sender. Like you I looked at the circuit diagram and I can't see there being anything else possibly wrong apart from the gauge.

I use my trip computer to monitor my fuel range as I find it very accurate.

 

i think the gauge is the issue. mine does the same thing and ive got a brand new sending unit.

 

Anti-Slosh module fixed mine

 

Anti-slush module?

 

Part number DAC7624. Located in the trunk

Like so:

Fuel Level RELAY JAGUAR XJS XJ12 | eBay

I would recommend getting it from jaguarclassicparts.com though. Its original and cheaper. Just choose "other country" at the start page and put the part number on the search.

There was another member who opened up his unit and resodered it, he never explained further details.

I ended up getting a new one and will probably get another just to have as back up.

This is typically the problem with facelift fuel gauges. The float on the senders does not tend to go bad like the earlier cars. Different material

 

Hmm...mine has been weird too, but I thought maybe it had something to do with the custom made, welded aluminum gas tank in mine.

 

Where exactly is that relay? I looked everywhere. Even my refrigerator!

 

Its on the trunk, you have to remove the trim on the left panel where the CD changer is if you have one there, and reach up higher and further. ......it mirrors the location of the fuel pump and other relays located in the trunk on the opposite side. Mine is a 95 AJ16, but according to the dagrams your 92 V12 should have it located in the same place.

 

+1 to Anti-slosh module. Fixed mine. Don't know when they started using them or if they did for the entire run. Looks like just another relay that they use throughout the rest of the car - not unlike the blue ones except black with white base.

 

Just adding my $0.02 here. This seemed to work for me too.

My fuel gague hasn't worked since I bought the car 5 years ago. It never showed full, and was often 'jittery'. The previous owner said it had been a problem. I found in the service records that the fuel sender unit was replaced 10 years before that.

I removed the fuel anti-slosh module, and looked at the PCB under magnification. All of the joints looked good, but some of them seemed to have very little solder on them. I reflowed most of the joints and added solder to the ones that were sparse. After replacing, my gague shows 5/8 full, which -feels- about right. It looks like this worked but I won't know for sure until I drive a bit and refuel the tank.

 

Mine has mysteriously started working again, been working for a couple months now. The sending unit sat for years in one position, so that probably was the issue.

 

As I have said in other posts on other threads, "An old thread but here goes..."
I can report that I changed the fuel sender on my 92 Coupe after trying to make sure that the gas level was below the port for the sender (it was...just) and after first being given the wrong sender unit (for an XJ6) I am very happy to say that a new sender unit worked and appears to have sorted the gas gauge issue. After fitting the dash swung rapidly up to about 1/4 higher than the old sender, and midway between 1/4 and 1/2 on the gauge.
As regards the anti slosh module the following link may be helpful..
Jaguar Enthusiast Vol 30 No.5
Very satisfying that all the work in running around sourcing the proper sender and paying large Canadian dollars for it had a great result...