When I first got my 01 xj8 I couldn't get more than 3/4 of a tank of gas in.
It slowly seemed to improve and although the last 2 gallons took an age to fill, as it keeps clicking off, I could fill up. The gauge seemed to be working well etc.
I ran it to Zero range today and its back to be a maximum of 3/4 of a tank. Any Ideas? Drives me crazy!

 

Use the forum search, another member recently posted the same problem, and motorcarman responded with several tsb's on the topic.

I had the same problem with my XJ6 and found that holding the fill nozzle so that the hose points to the opposite side of the car allows me to fill the tank. Others have found this to be true, so it's not just a quirk of my car.

 

Been trying to sort out this problem on my XJR-100 for the last year and a half. I've replaced everything that the TSBs suggest - even checked to make sure my fuel tank hadn't imploded - and no luck so far. At this point my suggestion is take it to the dealer if you can afford it.

 

Maybe the sending unit in the tank is going bad?