Chinese pump problem, help needed

[David.Soliman]

I got this Chinese pump for free when I bought my first pcp, the pump doesn't work properly for some reason. It is really heavy even when it is not connected to the rifle. When I connect it gets really worse, the pump locks in the up stroke, and I think it does not dump the excess air (or maybe does not draw in air, not sure).
The manufacturer claims 200 bars, but it is impossible to get past 80 bars. I'm six foot tall weigh 220 pounds so I'm not small but even with my full weight on it I can't move it.
I think it is an air venturi replica, but I don't have the schematics for it. Anyway I took it apart and didn't find anything wrong with it, except for some build up of humidity, I dried it and silicon greased all the O-rings. When I put it back together it was a lot smoother when it was not connected but when I connected it to the gun it was still very stiff and still won't pump past 80 bar.
Any idea how I can fix it??

[cdegrassi]

Hi,

you probably busted some o-rings and or need to rebuild all or some of them.
I am not sure if you will ever been able to get a rebuild kit for that brand, but try contacting the manufacturer.

Other pump manufacturers/resellers (Hill, AirForce, Benjamin, etc) offer rebuild kits.

In the worst case, and being very careful, you can take the pump apart and see if you can find what o-rings got busted and try replacing them with some from the hardware store.

Be careful if you lubricate it, not to use petroleum based products in the inner chambers or they will detonate (dieseling) and the pump will literally blow up.

Good luck
Cheers
Chris

[David.Soliman]

All the O-rings were in perfect condition, I replaced them all anyway but still same results, I use silicon grease for lubrication.

[Bentong]

If Chinese...try here > http://flyingdragonairrifles.org/FDAR%20Pump%20Guide.Lg.v1.pdf
could be something reverse or upside down. Breakdown is from Mike and you can visit his site or here > http://www.gatewaytoairguns.org/GTA/index.php?board=135.0

[David.Soliman]

The problem is I couldn't find any valves, no ball bearing nothing. Just one valve that is spring loaded, the valve is at the bottom I believe it is the output valve. It's not stuck or anything, I even took two coils off the spring to make it lighter, but nothing changed.