How's the Benji Pump Suppose to Work?

[ten4copy]

I'm trying to determine whether my pcp hand pump is working correctly. I got my Marauder today, and when I use the pump to fill it, some times I can feel the pressure both on the push-down and pull-up, but some times I don't. When I do feel the pressure on both the push-down and pull-up, I can tell that the air is getting into the reservoir. When it doesn't feel like this, i.e. on the pull-up it just slides right up with no effort, I can tell that no air is going in there at all. Is this what's suppose to happen? I'm thinking the pump is defective, but I'm not 100% sure. Any insight is appreciated.

Sorry, I know it's kind of hard to explain. Let me know if I need to clarify more.

[chuckster750800]

There is a small check valve in the bottom part of the pump that is suppose to close on the up stroke. It looks like it's made out of brass, has a small conical spring behind it and has a small o-ring on it's point to seal, so air doesn't go back into the pump on the up stroke. This is usually the first o-ring that fails in the Benji pump. It goes bad because of heat that builds in the pumping process or because of the crappy lube they use. You can get the pump repaired by sending it to Sun Optics for about $25. I'm not sure if they will just  replace that one o-ring or if they rebuild the entire pump with all new o-rings. There are about 12 o-rings total in the Benji pump. The Benji pump is a pretty good pump compaired to the others on the market and even on the Hill Pump site they reccomend re-sealing theirs every two years. Hope this helps.

Charlie,