Abstract: A fuel deflector and restrictor are disposed in the filler neck of an automobile fuel tank to inhibit filling of the tank with improper fuel. An opening in the restrictor permits insertion of and delivery from a fuel nozzle used with non-leaded fuels, but the restrictor obstructs a larger diameter nozzle used with leaded fuels. A resilient deflector member is cantilevered at one end and is biased toward and partly underlies the acceptance opening. The deflector is moved by the smaller diameter non-leaded fuel nozzle upon insertion, but deflects fuel impinging thereon from the unaccepted leaded fuel nozzle through an aperture in the restrictor to actuate the automatic shut-off mechanism of the leaded fuel nozzle.