A safety device for a fuel outlet to prevent delivery of highly combustible fuel to a motor vehicle with a running engine. The safety device comprises a fuel pump for pumping the fuel from an underground tank and into a motor vehicle. The device includes a sound sensor disposed below an area to be occupied by a motor vehicle adjacent to the fuel pump and is adapted to sense the sound of a running engine in an adjacent vehicle and a temperature sensor adapted to detect the engine temperature of an adjacent vehicle. Further, the device or system includes an RF radiation detector adjacent said pump for detecting a running engine, a data analyzer and a control unit for disabling the fuel pump when a running engine is detected in the vicinity of the fuel pump.