Abstract: An improved self-service gasoline pump is designed to insure payment for the fuel which has been delivered by the pump. The pump includes a switch mechanism which must be operated by the ignition key of an automobile prior to operation of the pump. Upon insertion of the ignition key into the switch mechanism, the mechanism automatically clamps and retains the key until the key is released by operation of a remote switch at the cash collection station. The switch mechanism includes a key actuated switch in the key slot. Upon actuation of the switch, a fuel pump circuit is closed and a solenoid locking circuit is also closed which causes the key to be clamped. A remote unlocking switch may be operated to release the solenoid locking circuit.