have you tried these? i've seen it before, and it looked cool, but saw some reviews where the fabric ended up disintegrating. but i don't know what kind of fuel or how long
Nope. I'd just plumb the sock to the lowest point of the tank......4 gallons in a tank that is left untouched is kinda 'off'. And they are a little pricey, but some guys got money to toss at a problem and some don't.
