I thought it would be helpful to consolidate some info Ive recently read concerning fuel tank venting, fuel return lines and the charcoal canister. Im no expert so correct me if im wrong and Ill edit the post. Camaros came with two types of gas tanks, one type had two lines coming off of it, and the other had three. The three-line tanks have a fuel supply, fuel return line, and the line to the charcoal canister. The two line tanks dont have the return line. You dont generally need to run a return line if youre running a mechanical pump. You do need one (highly recommmended?) if you have an electrical pump. You must vent your tank in some way or you will have fuel delivery problems. To vent your tank you can either leave the line hooked to the charcoal canister or you can install a small breather filter on the end of the line somewhere and remove the charcoal canister. You may smell more fumes if you do this. You can also use a vented gas cap to allow air into your tank.