Classic/Antique Car Repair: 1971 super beetle, charcoal canister, vent lines

Question
my 1971 super beetle has excessive gas fumes in the cab,  what could be causing this and how can i fix it.

Answer

73-trunk Terri,
 This is usually caused by a leaky or disconnected hose of the emissions system.  Specifically, there a vent lines from the gas tank which pass through a plastic "expansion chamber" under the cowl in the trunk (above and behind the fresh air box) which store and then route gas fumes to the charcoal canister under the right rear fender.  The attached picture is of a 1973 and later super(different than 71/72), but it shows what the expansion chamber looks like.  Perhaps a hose has fallen off; also the expansion chamber itself may be cracked or broken, especially at the connection ports on either end.

Here's a link to some more shots of inside the trunk of a 1971:

http://www.vwtrendsweb.com/tech/0308vwt_1971_beetle_super_project_part_2/photo_0...

Rick