Thuis is a post for posterity so that anyone running into the same issue might glean.

I have had gas smell every time my XK8 tank was almost empty or over 3/4 full. It got so bad this fall I could hardly drive it. I had played with some of the evap stuff but the same issue occured- 3/4 full, almost empty and when it was hot outside.

What was it you ask?

The weld where the filler neck connects to the tank had a hariline crack. A little epoxy and BINGO- no more smell.

I noticed a TINY smattering of rust around the area and guessed that it was rust from condensation vapor and I was correct. Cheap easy fix and now it is again a joy to drive.

 

good work.