Abstract: The invention generally concerns a submersible well pumping system comprising an axially elongated housing having a diameter less than the bore hole of the well, a multi-chamber hydraulically driven diaphragm pump, suspended in the well. The pump is driven by a self-contained, closed hydraulic system, activated by an electric or hydraulic motor. The flow of working fluid into and out of the working fluid sub-chambers is controlled by a two state main valve with a means to insure the main valve is completely switched, in turn controlled by a control valve which senses the differential pressure across the working diaphragm and generates a hydraulic signal to change the state of the two state main valve, typically when either diaphragm reaches the top of the pumping stroke. Singly or in combination, the means to assure the main valve is completely switched between the two states is an energy storage device, hysterisis in the control valves and or a two position latch the main valve.