A single action manual piston pump used to actuate fixed output positive displacement oil injectors. The unit can be used with Z Series Injectors, ZT Series Injectors and SJM Injectors. The pump incorporates an internal maximum pressure relief valve and a flow control valve to relieve distribution line pressure as required for normal operation of positive displacement oil injectors. Models are offered with a delivery connection outlet on left or right sides of the unit. A dual outlet (left and right sides) is also available.