Abstract: The present disclosure is related to an improved electrically-operated gear rotor pump mainly adapted for automobile fuel injection system; a dc motor in driving connection with the pump is housed together with the pump in a unitary housing. The driving shaft of the dc motor is in coupling engagement with the gear rotor pump by means of a floating coupling device having H-shaped longitudinal cross section. The terminal end of the dc motor shaft is defined in a rectangular form so that it can be properly fitted in the correspondingly shaped groove at one end of the coupling device. The other end of the coupling device is provided with a pair of symmetric semi-circular arms which are in registry with the identically shaped grooves axially extended through the wall of the inner rotor of the gear rotor pump with a fixed shaft, which is secured to the inlet end portion of the pump by interference fit with the inner rotor rotatably mounted thereon, located therebetween.