The present invention provides a fluid delivery system having a first chamber, a second chamber and a third chamber; a flow-through pump element separating the first chamber from the second chamber; a moveable pump element separating the second chamber from the third chamber; a first outlet in communication with the third chamber; and second outlet in communication with the second chamber. Additionally, the present invention provides methods of operating a fluid delivery system having a first chamber, a second chamber and a delivery chamber by reducing the volume of the second chamber while increasing the volume of the delivery chamber without operation of a flow-through pump element that separates the second chamber from the first chamber.