fuel tank breather
 

Hi
does anyone have a idea how the breather for the fuel tank works and where it is. i have noticed that the pump will make a wine sometimes. if i open the fuel cap it goes away , i also get a sucking noise the from the filler pipe.the engine then seems to run better too. i am thinking its related to my rough idle at times.
if i mess with the little breather in the filler neck the wine comes back aswel

i found a breather hose above the rear axle and its sucking air while the engine runs. i have also realized now i shouldn't drive through deep water with it being positioned so low.