I just went through this.

Drop the tank, install the fix for the cross over vent tube, replace
and use a gasket glue to adhere the rubber grommets in place. First
time I tried this I did not do this and that was a major problem
later. Use clamps to make sure the hoses don't come off and also
examine all the hoses and connections to the tanks just behind the
wheel wells. Be sure they are not clogged. I replaced all the lines
and secured them with clamps and adhesive on all the grommets and
since then no more leaks.

Regards,
Robert
NY

use this document, I found it very helpful.

On Sep 15, 2009, at 11:32 AM, Michael Kimball wrote:

> Gas overflows on ground when filling.  Any similar experiences or
> fixes?  I
> try to guess how  much to put in to avoid this.