Gas fumes...

If i have more than 3/4 full of gas and
take a turn, i can smell gas !
It seems to be from the cover for the
gas level 'float' under the rear seat.
I've replaced the gasket and hole
plastic/bolt/float unit (old one was cracked)
and still get slight gas odor when i
'shake it around'.
Anyone had similar problems ???
By the way, i have a 1983 scirocco.
I think they have smaller tanks than
most Sciroccos....