A manually-actuated pump for applying reduced-pressure therapy includes a charging chamber and a regulated chamber. The charging chamber has a closed end. A regulator passage extends between the charging chamber and the regulated chamber, and a valve body is adapted to control fluid communication through the regulator passage. A regulator spring is engaged with the valve body to bias the valve body against a differential between a pressure in the regulated chamber and an ambient pressure. The manually-actuated pump also includes an outlet port coupled to the regulated chamber; and a valve assembly coupled to the charging chamber to permit fluid flow through the closed end of the charging chamber.