Air Arms Hill MK4 Problem

[sjs]

Yesterday I could not pump my AA200T tank past 150 bar no matter how long I pumped. It is a few years old but has been used very little. The Hill troubleshooting guide speaks of a problem with the handle going back down on its own, but I have the opposite situation. My pump handle is rising on its own, and with considerable pressure. This begins very soon while pumping but I still get air in the tank if I pump long enough, but at 150 the tank simply does not receive any air. I cannot see any obstruction in the tank intake or the pump valve. Any ideas?

 

[Joedirt199]

You have to pull the check valve in the bottom of the pump shaft. It probably got water and gunk on the oring keeping it from sealing the air you just pumped from going back up the handle.