I tried searching this however the words being so short (and specific to my problem) are preventing any results. So apologies if this has been answered 1000X. My issue is the cap itself. It comes off fine, four or five turns and it's dangling by the strap. After filling up however I get one or two turns and it starts clicking, I can't get it seated far enough to close the fuel door.

When I got my first Disco a few years ago I got a code related to the pressure system which checks for leaks in the fuel vapor recovery system. Turns out the cap wasn't on all the way. This happened on July 4th (which is why I remember the incident so well) but I never had any issue with the cap between then and March the following year when I took the truck off the road due to frame rust.

A few weeks ago in my other truck I saw the attendant struggling to get the cap on after filling up. I noticed he wasn't able to get the door latched closed so before driving off I tried it myself. About two turns and it started clicking. I went home and swapped the cap from the rusty truck and the old cap screwed right down tight. Next fill up, no issue with it then either. Last night however I filled up and the "new" cap did the same thing. 2 turns and all clicks. A few hours later it screwed right down again. I tried the original cap to this truck (which is now on the parts truck) and it screwed down tight as well. There doesn't appear to be anything visibly wrong with the threads on the neck or the cap.I don't understand why they are finicky after initially being removed, and then work ok later. Is this a sign that I simply need to buy a brand new cap?

 

The caps and necks for these are finicky and prone to poor construction, and any aftermarket caps just make things variously worse. I tried a number of caps to resolve the emissions leak issue and finally gave up and bought a genuine LR part. Cost more, but it completely fixed the problem, so it was worth it in my book.

 

I lucked out with an ebay knockoff from LK8 or somewhere. No issues in 1 year....

 

Stant originally made the fuel caps for LR

 

Thanks for the replies. It occurred to me I could probably just swap out the caps back and forth on each fill up and hopefully avoid the problem entirely. It takes a truly lazy man to come up with an easier solution

 

Scotchbrite the filler neck threads, and get a basic Stant gas cap.

 

Seems like they expand over time.

I ended up getting a cheapo Slant one and then pulled both the stock one and the new Slant one apart. Was then able to reuse the stock top and retaining strap but with new and working parts underneth.

 

Yep been doing that very thing for years now.

 

what does Scotchbriting the filler neck do really?
sorry I am good for dumb questions lol

 

It cleans the crap off of the threads.