again I would just hook up the system with the vapor seperator and purge canister. It works great like the engineers at toyota or chevy or whom ever designed it. If you use the filler cap that vents you still have pleanty of opportunity to smell gas - which I hate especially in my garage. The way I hooked mine up I never smell gas when driving or parked.....peesalot said:Caping off #4( all 3) is going to depend on your gas cap. If the only vent is #3 then the cap should be of the positive locking type that blows the pressure at a certain lbs. Or you may have the stock cruiser cap that just lets air out and fuel to if you are sidehilling or twisted up. I put a filler from a late model dodge pu on ( 3 hole mount ) but the blow off spring lbs was a little to hi cause every time you opened cap it blew like a whale. So I ran 1 of the seperator lines to a cage top breather.