Abstract: A method and apparatus for pre-charging the pump chamber of a discharge pump on a container such as a fluid atomizer primes the pump for dependable operation thereafter. The method includes opening the outlet valve of the discharge pump by operating the pump to its full displacement, and applying a vacuum to draw container contents into the pump chamber, just up to the outlet valve. The apparatus for practicing the method includes a controllable vacuum head adapted to engage an outlet channel of the container, the vacuum head also being movable to engage and move the pump. The apparatus can incorporate an indexing feeding arrangement for delivering articles to the vacuum head, and a blast of pressure may be applied upon completing the process, to release the containers from the vacuum head and securely close the pump outlet valve.