A gas lift system for oil and gas wells has a gas pump. The gas pump comprises production tubing, a chamber, a dip tube, check valves, a gas supply line and control valve, a gas vent line and control valve, and a fluid control line. Liquid is pumped to the surface by allowing it to collect in the chamber and then forcing it out of the chamber with high-pressure gas. The gas supply and vent valves preferably are controlled by a single pressure control line. The system preferably included retrievable valves that may be installed through the production tubing to provide a life-of-the-well gas lift system.