Erratic Fuel guage

[peterirvinharrison]

I've got a problem with my fuel guage behaving erratically on my '93 4.0 XJS. Has been behaving strangely on and off fort a while, but after filling up today it was oscillating between 3/4 full and empty (with the low fuel light on)....and its now just showing empty with the warning light on. I've seen some old posts on the forum suggesting this can be a temperamental guage, and references to anti-sloshing relays.....anyone else had this problem or have any suggestions what to try? I'm supposed to be going on a rather long road trip shortly, which I don't fancy without a reliable fuel guage!!

[almcl]

Had something similar a few years ago on my '93 4.0.

As I recall just after a refuel to full, the low fuel warning light came on. Can't remember if the gauge also played up but a replacement sender cured the problem, although I can't now find the invoice for the part. (Odd, as I keep all invoices, as a rule.)

The genuine Jaguar price does seem a tad excessive, after a quick look on the Jaguar Classic parts website!

[ptjs1]

peterirvinharrison,

The easiest way to check if it's the anti-slosh relay is to remove it and use a bypass wire on the holder. If you search the Forum, you should find threads where I've described how to do this.

If you can't find the answer, post back and I'll detail how to do it.

Cheers

Paul

[ng4xjs]

These were previously available for £75, SNG but I'm sure this is no longer the case. I ran my last XJS for the best part of 15 years with a dodgy unit (anti-slosh). I was fortunate in that when I turned the ignition on mine registered more or less correctly for at lease 30 seconds before dropping to 1/4 full where it stayed until the next time.

Nick

[peterirvinharrison]

Thanks for the comments guys. I've now used about a half tank of petrol, and it seems to have settled down a bit. In fact its now displaying similar symptoms to those Nick describes. Clearly filling the tank nearly full freaked out either the sender unit or anti-slosh. I'll keep an eye on it , but may need to test the anti-slosh if it gets worse again.

Paul...I have seen several of your old posts .....if I do remove the antislosh module, is it obvious which terminals I need to bridge to bypass the unit?

Many thanks,
Peter

[ptjs1]

Peter,

If you remove the module to test it, you need to bridge the terminals on the holder that correspond to the pins of the module as detailed in the pic below:

The wire colours on the holder that you need to bridge are the light green wire terminal (which is the voltage input feed from the tank sensor) and the brown/ pink wire terminal (which is the output voltage feed to the instrument gauge). I made up a wire with a spade connector on each end and just inserted it in the holder as shown below (forgive the blurred image):

Hope this helps

Paul