Abstract: An in-tank fuel pump apparatus includes an elongated motor-pump unit having a motor and pump unit connected in end-to-end relation. An outer cam has a substantially constant diameter enclosing the motor-pump unit and projecting axially outwardly therefrom and defining a control chamber immediately adjacent the one end of the motor-pump unit. A control tower is secured to the end of the motor-pump unit from which the motor cam extends. The control tower includes a body member having a closure plate abutting the motor pump unit, an outlet passageway extending axially from the motor-pump unit to the exterior of the motor cam, a pressure sensor secured within the body member having an inlet connected to a sensing passage connected to the output of the motor pump unit in an outermost circuit board forming the outermost end of the tower unit.

Abstract: An in-tank motor-pump unit includes a motor driven gear pump, a pressure transducer, and a control module as a single integrated package establishing fuel flow at a constant pressure by creating a pulse-modulated motor drive having a fixed "off" and a variable "on" period. A permanent magnet DC motor drives a rotary pump with the required torque operating over the specified speed range and without stalling out at low flow demand. An integrated circuit board includes an IC timing chip, operating in an astable mode, has an input connected to the transducer and an output connected to a MOSFET switch which connects the motor to a power supply. A series resistor connects an amplified voltage signal of the transducer to charge the capacitor and discharge resistor separately connects the capacitor to the input of the timing chip to generate a constant "off" period and a variable operative "on" period of the MOSFET.