Bontrager Charger Pump blowing back - is it broken?

[Paulisabout]

Hope I am not going mad or missing something. I am trying to inflate a MTB Schrader valve and when the pressure starts to build it just blows back into the pump. Eventually forcing the handle up and making it impossible to get past 20psi. I have taken the thing apart and cannot find any broken parts or missing seals. It was working fine? Any ideas out there? /img/vbsmilies/smilies/mad.gif

 

[64Paramount]

No, it shouldn't be acting that way. Is that a new pump? If so, I'd just take it back and exchange it for another.

If exchanging or returning it isn't an option, and no one else here comes up with a better idea, I would email Bontrager about the issue using the following link and then clicking on "contact us".

http://www.bontrager.com/support

 

[davereo]

The pump has a built in check valve that allows air to flow into the tire on the down stroke. On the upward stroke the vavle closes and allows air to enter into the pump. It may have picked up a small particle of dirt or dust which is not allowing it to fully close. Try putting a few drops of lubricating oil in the hose and pump air through the nozzle. This may free it up. If not you may be able to undo the top of your pump and pull the piston all the way out of the cylinder. Squirt a few drops into the cylinder and reassemble.
Good Luck

 

[Paulisabout]

I'll give that a go. Where exactly is the cut off valve - there doesn't seem to be any moving parts apart from the piston and the locking arm on the head?

 

[davereo]

A check valve can be constructed many different ways. Simple valves are generally just thin leafs of metal that are thin enough to react to air flow flexing away from base to allow air to pass. Kind of like the vibrating leaf of a New Years noise maker.

 

[Paulisabout]

Does any one know where the check valve is in this pump. Just snapped off a valve trying to pump - so not happy!