It's the vent hose that's leaking. It's about a 2-foot section of rubber tubing and has been coiled into 3 loops that sit higher than the tank.

I'll be in to town tomorrow and will stop by an auto parts place to see about the roll-over check valves.

All the best,

John

1953 Chevy 3100 Resto-mod
In the Stovebolt Gallery
http://www.john-ayearst.com/la-noche-53-chev-pickup/