Can;t get gas up to carb

Well this vent line is a 2 piece. I disconnected at about under the passenger seat, where the rubber line connected the 2 and it was clogged all the way to the front. I will give it a try over the weekend with the gas cap off and see how it works. It's funny to here I had a friend stop in and said both his 68 Cudas did the same. Seems like that would lean the motors out, when the carb is not getting the gas it needs. It may be a epidemic in these old cars. Everyone might want to check there vent lines.