Naw, it ain't! The evaporative emission control system does no harm, and directly saves you money. It traps and condenses gasoline that would otherwise float off into the air, so you get to use the gasoline you bought and paid for. It also reduces gasoline stink when the car is parked in an enclosed space (like your garage). All benefit, zero drawback. It's a stone-simple system; if the lines are messed up just correct their routing and call it good.
