fuel tank not venting

[jfp3205]

Can someone tell me about this?
when i remove th ecap from my front tank, no sound is made but when i take the cap off the rear tank, it sounds like air is escaping. Are these tanks vented and is it just my fuel cap that is bad or do i have another problem?
Thanks for all the help

 

[jonathan]

Take the role over valves out that will fix it

 

[rhkcommander]

using the wrong cap will make a seal too... I did find some locking DIESEL caps that I'm gonna try out. I couldn't get my truck to start and the electric lift pump was loud so i popped the cap off and heard airflow and the epump settle down

 

[franklin2]

My 89 had factory hoses coming from the top of each tank, and they were clipped onto the frame with a little plastic cap. Check these out if you have them.

But I can't believe you are still running or trying to run the factory system, and one of them sounds like it's clogged. How in the world do you get fuel into it at the station without it foaming up all over the place?