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 have a similar WF pump, and have had a similar problem. It's most
noticeable when inflating a new presta tube. I've had good luck with
either blowing a little air into the tube by mouth or pushing the valve
stem into the pump far enough to force the valve open by contact rather
than relying on air pressure.

JLS