Alright so finally decided to take my air pump off yesterday, my question is why do I do with the neck that come out of near the back of the pump. I noticed that with it off it draws air in when i rev it and then pushes it a bit? How do i cover that?

 

however you want....
why did you take it off anyway....?

:AA:

 

You can either make a blockoff plate for it, or purchase one from Racing Beat. They don't cost much.