Okay, I’m still too dumb to get it I guess… I see that vent tube run from the tank to the top of the filler tube, which makes me think it is still a closed loop if the cap is not vented. Where does it actually vent out to the air to prevent the tank from sucking vacuum?
It goes thru the floor plate for the filler tube any liquid fuel would just drip on the ground. It is looped upward to keep the tube clear of any liquid fuel.