as it turns out, I too have one that does not spew CO2 over he landscape (the Zefal)
Didn't do me much good today when I got a flat about 15 miles from home. Bought it last summer and have not had to use it untill today. After a year or so of nonuse, it decided not to be of use at all. Thanks to the woman that picked me up and drove me home. Was in a remote area without phone, looking at a long walk home.
I bought a new bike last fall after accomplishing some goals, my old one was a 30 yr. old with a nipple for the pump, and it fit well. New bikes just don't do Zefals well, at least not mine. I've had to mount it vertically on the front stem with a couple of straps. Still, it bounces away on the roads I ride, doesn't come off but I need to stop and reset it too often. Anyway... after never using it for a year untill today, it seems the road water and moisture just got to it. I'm in a fairly remote region and I'm looking for something better. Or maybe I just got a bad pump.
I don't know the answer, but I'm just an occassional bike forum poster and visitor who is on now because I had to hobble home on a really fun after work ride because my pump failed me.
just sayin........