A gas pressure driven fluid pump having a pump tank with a liquid inlet and a liquid outlet. A float assembly is carried within the interior of the pump tank and is movable between a low level position and a high level position. A compression spring is connected between the float assembly and a pivot member. Due to the force applied by the compression spring, the pivot member rotates to a first position when the float reaches its high level position and rotates to a second position when the float reaches its low level position. A valve assembly is connected to said pivot member to switch between motive porting and exhaust porting in a snap over fashion due to rotation of said pivot member between said first position and said second position. A damper system may be connected to the valve assembly to slow movement of the valve assembly between motive porting and exhaust porting.