Why is this happening?!!Please help.

I pulled a sock out that was so rusted that soaking it in CLR didnt do squat and when I pushed air through it it blew up like a balloon and popped with a cloud of rust. That sucka was plugged! On a whim, I applied compressed air to my fuel line and it inadvertantly popped out a dent in my gas tank! I dont know where the vent is but I think its tiny. All new hard fuel line wont put you back 20 bucks.