Abstract: An anti-theft device is provided for vehicles and equipment powered by engines having an electrically-controlled fuel delivery system, and particularly for engines having a shut-off solenoid in combination with the fuel pump and governor assembly, which solenoid operates a valve to stop the flow of fuel to the engine. A lock switch is inserted in the electrical connection to the solenoid. There must be continuity across the lock switch for operation of the engine. The lock switch is preferably positioned substantially adjacent to the fuel pump and governor assembly. A first lock structure is secured to a fixed portion of the vehicle substantially adjacent to the lock switch. A housing is adapted to fit over the lock switch so as to substantially prevent access to the lock switch or the shut-off solenoid. The housing includes second lock structure adapted to engage the first lock structure so as to secure the housing against removal to prevent unauthorized operation of the engine.