It could be you've got the pump head pushed too far onto the stem. If it's not a deep head, it's easy to have the bottom of the pump head push the valve screw doo-hickey in while pumping. This lets air flow out as well as in. Try not putting the pump head very far onto the stem.
Drew Ellison Everett, WA USA
On Nov 1, 2006, at 8:24 AM, lennys_email@juno.com wrote:
> Greetings All:
>
> I've got a Silca that won't inflate a tire and I'm not sure why. Its
>
> got the chromed oval type plastic head with a single rubber plug
>
> sized for presta that fits inside a white nylon cap. It seems that
>
> air does get pumped into the tire, but is immediately released on the
>
> return stroke. Is there perhaps a part missing in the head, or could
>
> it be an issue with the pump itself ? BTW, the pump is NOS.
>
> Thanks.
>
> Len Grossman
> S. Orange, NJ