74 Superbeetle vert not quite there yet

I've been working on my 74 Superbeetle convertible since I bought it in January. My wonderful father in law has been helping me. But now I have it home and there's still plety to do, although it is running great!  Let's start here. When I fill up he gas tank there is a STRONG smell of gas coming from the tank area. No leaks that I can find. Funny thing is, the smll goes away when the tank gets to be about half full. Any ideas

Oops. Sorry. I was the one who misplaced the tech post.  Sorry Amanda! Well, I'm a new member after all.  My dad put himself through school as a VW mechanic in the 60's. As I grew up we always had them. I remember one in particular - a squareback. When I was 16, I learned to drive a Rabbit and that ended up being my car in college.  Years and years later now (I'm turning 40), I bought a 74 Superbeetle as a project to spend time with my father in law.  It's been a lot of fun and now I'm driving it to work a couple days a week.  I hope I can get to know some folks here and maybe get some questions answered. Thanks!