Yes you still have to vent the tank. The idea that I had was to run a line out of the top of the tank but rusty's Idea is alot easier you just drill and vent the cap. Or buy one that is vented already it does the the same thing as my idea just much easier. When gas gets hot it expands have you ever seen a full gas jug at the end of the day when you been mowing all day? It's all swole up thats the same thing your tank will do without some sort of vent. The return line simply relifes that same pressure that's made at the fuel pump and in the fuel lines and gives it a place to go. Back to the tank.
