I recently purchased a Readyair unit used. I have tanks from 3 different manufacturers all with quick disconnect foster fittings. It will only pump up one of them. With the other 2 the fill pressure builds up within less than a minute and the pump shuts off without putting any air in the tank. My Hill hand pump works without issue on all 3. The tanks were all around 1200 psi before I started and I had the fill pressure set to 2000psi. TC