The easiest way is to get a vented cap. The correct way is run both the vent lines into the special liquid vapor seperator, which in turn goes to the canister. This stops the liquid fuel from slugging the canister, which will ruin it. Go to your local Mopar dealer, and have them look up the seperator number for about a '94 YJ with the small 15 gallon steel tank. Then look at the picture, and you can easily see how it goes. Probably about $12 with the special hose.