Pressure building in tank

I'll look at the inside of my cap. I'm not sure how to pull off the line to the canister. The clip isn't adjustable or flexible. I've never seen a clip like it. I do not think these two issues are interrelated. Just brought them up at the same time. Sorry. I have not plugged the heat crossover in my performer intake. I've heard Eddy carbs are more prone to this issue. But swapping a carb right now isn't what I'm wanting to look into.

Kiss, how do you like that cool carb plate? I had been looking into them. Was gonna wrap my fuel line first with header wrap and go from there. Thanks for the conversations guys. I appreciate it.