Brad Ford wrote:
I've got a cool little Wrench Force floor pump that will accept
Schrader or Presta. I've used it for over a year exclusively to
inflate my Presta road tubes. Got the kids bikes for Christmas, pumped
them up (Schrader valves), and now (several weeks later) the pump won't
blow air out the Presta hole any more. It's supposed to be "auto
sensing". Is it just buggered? What would you all try to debug this
problem?

My Beto brand floor pump sometimes balks at starting to inflate a
Presta tube. I find if I put my finger against the tube's valve (from
the far side) to increase the back-pressure, the pump catches on and
inflates it properly.