Fuel gauge lunacy
 

Not really that bad but the fuel gauge isn't telling me the truth any more.

Having put about half a tank of fuel in about 10 miles later the fuel needle starts to visibly drop and within 3 miles I had allegedly dumped well over a quarter of a tank of fuel to the extent that I pulled over before attempting to get over the hill to do the last quarter mile home. You really do not want to be stranded on this hill with the narrow road.

No smell of fuel, no evidence of leak so I assume there's plenty of fuel and drive home. Have a nice cup of tea, go back to car and check the gauge and it's showing just over half full and that's what I'd expect.

However, yesterday I put 40 litres in and the gauge went nuts for while and then settled back to the quarter full it showed before refuelling. As I drove home the needle crept up (as did the range indicated by the computer) until it was a bit under half full.

Edit: I just checked the gauge now and it first went to 3/4 full which is what I believe it should be, did a little dance and decided that there wasn't that much after all, just a bit above one quarter full. Bother.

I'm assuming the sender has some sort of problem and that I should wait until the tank is getting on for 'low' and take the sender unit out of the tank. Take a look and see if there's an obvious problem and replace. If there's no improvement then replace sender.

Or, am I being too simple minded?

Mike

Almost certainly the sender. Easiest job you'll ever do on that car :)


Cheers
DD

Doug is right. I just did this fix. I attempted to clean mine first with no change in issue so replacement is almost certainly a must.

Get this part:
https://www.fcpeuro.com/products/jag...-xjr-dbc012042

Remember to change out when you KNOW the fuel is low. The rear access area requires the tank be low or it will leak out! It also won't hurt to have the car's nose pointed down hill either by slightly lifting rear end with jack/stands or on a tiny hill. Open the back panel of your trunk carpet (vertical back piece). Get a hammer and a flat ended object ( I used flat end of a file) and gently tap counter-clockwise and you're in there. Also be sure of which terminal each connector goes on. I always take pics with my phone before I start taking things apart. Put in the new part, slightly twisting while inserting for clearance and put it back together. Slightly tap closed and give one more tap for safety.

Dang not this part then?

Fuel Tank Sender - DBC10284 | Jaguar XJ40 | Jaguar | British Parts UK

Yes same one. I didn't realized you were in the UK. You can get it locally.

Actually I have found a place quite nearby that sells the part you mention so I can have the pleasure of dropping in and getting the part en route to Wednesbury which I have to visit from time to time.

Now, as a public service if any you non UK guys are making a visit here do not make a point of visiting Wednesbury it really is a very sad place. I'm not sure what heavy industry it depended on but it's all gone now.