No need to seal anything. You need to keep the vent in the tank, just no longer have the hose running up to the inner fenderwell, or else you will be smelling gas fumes in the cabin with it no longer hooked to the charcoal canister. Just tie up the hose somewhere in the rear of the car. You could just not use a hose at all on it, but I figure with the hose running up before it turning back down, there would be less chance of fuel sloshing out. I would assume it had a one way chack valve in it to prevent fuel from leaking out in case of a rollover, but seeing it was designed to be a sealed system in the first place, it may not. Its not any more dangereous than a carb draining its float bowls in a rollover.