Thanks for the quick answers, I really appreciate it.  Also, thanks to Mike for the explanation of the valves, I used the term "float" because that is the most similar comparison  my limited knowledge allowed.  This list is invaluable!
 -------------- Original message ----------------------
From: Mike <mbucchino@CHARTER.NET>
>   It won't damage anything, but it could be condsidered a bit of a fire
> hazard just sitting still.  The gasoline vapors will be released to
> atmosphere at the leak points.  You'll smell fumes on a hot day, and at fill
> up time.
>   I drove my van with a broken plastic crossover vent tee for almost a year
> before I did a reseal.  The crossover is connected to the same vent lines as
> the expansion reservoir check valves.
>   They are not 'float' valves; they are weighted check valves that will stop
> the flow of fuel in the case that you (accidentally) fly inverted.  Any
> leaks along this system will result in an unsafe (and polluting!) condition
> due to fuel vapors being released to atmosphere, instead of being trapped
> and re-introduced to the intake upon startup.
>   Don't totally top-off the gas tank (to prevent overflows), and expect some
> gas smell when you approach the door on that side of the van, until you get
> it resealed.
>
> HTH,
>
> Mike B.
>
> ----- Original Message -----
> From: "Taeke" <taeke.t@GMAIL.COM>
> To: <vanagon@GERRY.VANAGON.COM>
> Sent: Thursday, July 03, 2008 2:56 PM
> Subject: Re: Driving without fuel expansion tanks hooked up?
>
>
> I need a reseal what's a float valve?
>
> -----Original Message-----
> From: Damon Lowe <dlowe93@COMCAST.NET>
> Sent: Wednesday, July 02, 2008 11:00 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Driving without fuel expansion tanks hooked up?
>
> My wife suddenly decided we need to take the westy to see fireworks this
> weekend, which would normally be super cool.  However I currently have my
> fuel expansion tanks out while waiting on some "float" valves that broke
> while doing a tank reseal.  Will I damage anything if I put a small amount
> of gas in and drive it with the lines to the charcoal canister unhooked?