The blue accelerator pump was current production until Zenith went out of business last December (thanks to all those buying the chinese knock-off junk, one more quality American company bites the dust after more than 100 years!).
Originally, Zenith offered a metal accelerator pump plunger, but if allowed to sit for a couple of years, it would sometimes rust.
And yes, the force of the spring would cause the accelerator pump to pump.
Jon
