You shouldn't need to. The vapor can should never have liquid gasoline in it.
Did the tank get filled extra-full? Because unless you've got some fuel/vapor lines mixed up, this should not ever happen.
'91 Frankenheep YJ. 4.0, 4" BDS, Richmond 8.8, Titan 12k, 35" KM2's, rust.
'88 YJ, 4.2/4.0 head, +4½" & shackles, BFG 33's (sold)