i've been looking at fuel cells and notice than some come w/ a seperate vent and return fitting and some without. some fuel cells alos have a little vent system built into the cap so air can be let in to displace the gas as it runs down...

so i guess i'm wondering if you need a vent and why some dont have it.

 

cmon, anyone?

 

You definately want a vent, and it should have a line on it running outside of the car. The vent should have some kind of check valve to keep fuel from coming out in a roll over.

 

why do some tanks not have vents? how do you add fittings to a polyethelene fuel cell?