I have a w 150 and do the charcoal canisters supposed to suck air out of that breather looking thing

 

it might. i don't know how they are suppose to work but they do have vacuum pulling on them to suck the gas fume into the engine.

 

post a picture.
when the manifold vacuum draws to purge the cannister...air must come in from somewhere. this air should be filtered. not sure of your build...most stuff either has a filter on the air line or internal to the cannister. my 84 Pontiac had a filter on the bottom of the cannister.