I've got a lazyne micro floor pump (this one: https://www.lezyne.com/products/hand-...loor-drive-hpg)

There is a problem and I can't figure out what to do. The pump will compress down but obviously the air is being compressed inside the pump itself, not exiting into the hose (I took the hose off and nothing came out).
I feel like I'm missing something obvious. Has anyone else experienced this? I can't tell if it's busted or I am just overlookign something simple.

I appreciate any help.

Thanks.

Silly question, perhaps, but did you unscrew the Presta valve and tap it to make sure it's not sticking?

Hold your thumb over the opening in the head. Can you prevent yourself from pumping? If not, the plunger is not air-tight. This means rather than compressing the air, it's just going down, passing the air.

Unscrew the shaft and examine the plunger gasket. Perhaps it's dry or misshapen. Grease it on the inside and outside and try again. It may need replacement.

Thanks for your answers. Perhaps i can describe it better.

No air is coming out of the hose. I took off the hose, no air comes out of the hole at the bottom of the pump. The problem seems to be that it's TOO air tight, if that makes sense.

I think I will have to unscrew the shaft like noglider suggested. I'm not sure how to do this. Now I'm back at work so I'll have to wait until later to try...

Is there a trick to taking apart the plunger?

The shaft should be screwed to the barrel at the top. Unscrew it.

The plunger is just a gasket. It might not be round any more. It might look round, though. It might be round when it's in your hand but it might deform when you put it back in. Grease it. That may be all you need to do.

By air tight, I mean the plunger gasket is supposed to take the air at the top of the barrel and push it down. If the gasket is shriveled up, it will move within the air rather, like a small ball. That turns your pump into not-a-pump.

If you removed the hose from the pump and no air comes out when you try to pump it, it sounds like the check valve is stuck. I don't know how you would unstick it.


I have an older version of that pump, and I checked it when I got home, I can make the same thing happen when the pressure gauge is turned backwards. So try reversing the pressure gauge.