Gas smell when tank full

I've been working on my 74 Superbeetle convertible since I bought it in January. It is running great!  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 smell goes away when the tank gets to be about half full. Any ideas?

tank should be vented so i would guess your just getting a whiff of the vent tube .. mine does it too

mine used to  do it to  the vent  line is hooked up  to the main fuel line   the  fill  line.  it had some  crappy  cloth like hose on it  about  1/8 inch and when i filled up,it  would slosh thru the line and saturate the vent line and  man did it smell  .

mine did this too what i did to fix this problem was to change the line for my ventulation

    Worked on those things long ago at a dealer, and also had my
 own VW shop for years, That gas smell your getting is the vent
 tube, they should be replaced and vented under the car, if you
 look closely you will find a small hole for the tube to fit into and
 exit the vapors under the front of the car, also the gas cap will
 get a bad seal and you will get vapors there.