My pump has the dreaded bounce. Where you pump but the pressure doesn't go into the tube. What makes that "one way" air flow happen? Ugh. I hate having to ask or not knowing. Of course I've done nothing to change the pump. It worked last week. So I just now took everything apart that comes apart and put it back together. I saw nothing that helped me understand how a pump works. And it still doesn't work. Just bounces. Well, it'll put 40psi in. That's it. I see it read on the dial when I hold the handle down. Then the gauge goes back to zero when I let the handle rise up. Sigh. Of course I also don't know how to describe what is happening, but I'll try the search "pump bounce"?
[UPDATE!: HA! looks like i had the same prob a few yrs ago and posted here. here's the thread with the solution. actually, here's the solution. tho i haven't tried it yet this time! ...don't dismantle the pump guts, especially from the base. unscrew the side knob near the gauge and fish out the spring, maybe lube it, then put it back. done. here's link to more:
https://www.bikeforums.net/bicycle-m...blow-pump.html