On Friday, February 3, 2006 at 7:20:58 PM UTC-5, 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?

I had let my road bike tires go completely flat then encountered the same problem when I tried to inflate them, with a different brand of dual-valve floor pump that had always worked until then. I tried the trick of covering the open Schrader valve with your thumb, but it didn't work for me. It did cause a lot of pressure on my thumb and some very entertaining noises when air squeaked out! What ultimately worked was to inflate the tires of another bicycle (which also uses Presta valves) which had mostly full tubes already, then go back and inflate the flat road bike tires. It seems that persuaded the pump to switch back to its Presta setting. Good luck to all!