Abstract: A fuel system for vehicles having two gasoline or diesel fuel tanks includes a single filler port fitting having a Y-junction located close to the mouth of the filler, so that, when the user is at the gas pump, the spout of the fuel filling hose may be directed into either of the branch channels to fill either one tank or the other tank, selectively, or may be employed to fill both of the two fuel tanks. In addition, venting arrangements from each of the tanks are coupled to the filler port fitting to accommodate smog reduction requirements.