Abstract: A precursor dispensing system includes a source, an ampoule, a first valve, a second valve, a line charge volume container and a controller. The source supplies a liquid precursor. The ampoule receives the liquid precursor from the source. The first valve adjusts flow of the liquid precursor from the source to the ampoule. The second valve adjusts flow of a precursor vapor from the ampoule to a showerhead of a substrate processing chamber. The line charge volume container is connected to a conduit and stores a charge of the precursor vapor, where the conduit extends from the ampoule to the second valve. The controller: opens the first valve and closes the second valve to precharge the line charge volume container; and during a dose operation, open the second valve to dispense a bulk amount of the precursor vapor from the line charge volume container and into the substrate processing chamber.