A pump system having a main pump and a plurality of subsidiary pumps each of which has a relatively low pressure compartment from which fluid may be pumped to a relatively high pressure compartment. The main pump preferably operates continuously, but each of the subsidiary pumps is inactive until such time as it is elected to be operated, whereupon high pressure fluid from the main pump may be directed to such subsidiary pump. The pump system is particularly adapted for use in conjunction with an automotive engine.