Hi, I'm about to remove the charcoal canister from my CRX, and I was wonder if I should place a one way valve on the breather hose from the tank, to let the fumes out. but not take air in. Wouldn't leaving the nipple at the firewall free-to-air be a vacuum leak (since it's behind a 2-way valve)? Or isn't there supposed to be vacuum in the fueltank? I was under the impression that the charcoal cannister was in a closed loop, so there had to be vacuum in the fueltank. But then I noticed another hose, on the bottom of the charcoal cannister (which doesn't show in the vacuum diagram). So it pulls in air that way?