I just acquired a used Zefal hp double shot floor pump and I cain't seem to get it going. It's set up for presta valves and I've managed to get it to stay attached, but it will only get the tire slightly inflated and the guage goes back to zero after each stroke. Am I doing something wrong or is it shot?

SKeown

try a different pump, maybe it's you? I hate most floor pumps, they are typically junk. Silca Pista is the best and will last for life. I also have a craftsman battey powered hand compressor with a silca head on it goes to 200psi AMAZING I love it.

https://www.cxmagazine.com/craftsman-...mal-conversion

All floor and frame pumps have a " check valve", usually at the base of the cylinder. It allows air to flow in one direction (pump to tire) but prevents back flow. I assume the one in yours is clogged or dirty and isn't seating properly. These are usually bearing balls or a flapper and lightly spring loaded in their seats. Try looking at the base of tyour pump under the pressure gauge or inside the hose attachment port.

Unlike rithem, I've had excellent service from Silca, Park and Meidai floor pumps. Clean yours up and it should work for years.