2100 pump problem

[Leviathan]

I just got done checking my brother's arsenal, and his biggest weapon, his CPS 2100, has a problem I've never encountered before. When pumping a filled reservoir, the pump will jerk from 1/4 to 3/4 back on the backstroke. It moves smooth on the outstroke, and smooth both ways with no water in the tank.

Any ideas?

[HBWW]

Happens to mine too sometimes, not sure what causes it.
(I have to do some repairs too)



Edited By C-A_99 on 1176348962

[XP20Warrior]

I would think that the rubber that's ramming the air into the tank is not lubricated or such. isoaker_com might know.

[isoaker]

Basically, when it's pushing water, it experiences differing amounts of resistance when pumping? As XP20Warrior suggested, it's probably from some wear on the rubber seal and inner lining of the pump shaft that results in some additional sticking points inside the pump shaft when pumping water. I've noticed this problem on some of my older soakers like an older XP150. I also damaged my first SS50 by pumping water with its pump (by submerging the whole soaker in water to fill). You only feel the sticking when you need to pump something that causes more resistance (i.e. water) that compresses the rubber plunger to fill the pump shaft more as opposed to low-pressure air.

[SilentGuy]

I've noticed several guns doing that, like my Argon. I don't think we know enough about the problem to conjecture, although Ben might have found some information for the huge SSC update.

With pressurized-reservoir guns (where air is pumped into the reservoir), there's a little bit of dead space between the pump and the check valve into the reservoir. Some of the pressurized air stays in that space, and after you pump, it expands and pushes the pump out a bit.

[Leviathan]

It's almost like theres a trip point where it disengages a spring and jerks the handle toward the trigger, it's really wierd.

[forestfighter7]

This has happened to 2 of my guns as well. I suggest cleaning the gun out with soap and water. There may be some kind of contamination in it. When I did this it worked. If soap is bad for a gun(which I doubt it is)will somebody please post so.

In my gun there was dirt in the pump shaft. I had to open it up and clean it out. This might be necessary.

[SSCBen]

This problem is caused by some sort of negative pressure being built up in the pump. This can be caused by pumping air or by having something obstruct flow so that you're pulling on a vacuum. The problem shouldn't occur on a full reservoir unless something is obstructing flow. That something could be a kinked tube or a clogged valve.

With this being said, I have not encountered this problem myself aside from when pumping air. Having something stuck in the valve or a kinked tube is speculation. I would suggest investigating the problem and reporting back here. Open up your CPS 2100 and get a better look. You wouldn't believe how obvious some repairs become once you open up your water gun.

Generally, to open up a CPS 2100, you have to first remove the black pump cap on the end. Typically you have to saw it off, but some pop off with a screwdriver prying them off. After that, you can remove the screws and open up the water gun.

[Leviathan]

Oh boy, Im sure Bryce will be thrilled that im gonna saw the end of his gun off :p

He'll get over it, thanks for all the suggestions guys, when I get some time I'll open it up and see if I can find whats wrong.

[SilentGuy]

Ben's suggestion is the most common sensical. And even if we did know the problem, you'd have to open up the gun to fix it.

The attitude with opening up water guns should be "it can't get any worse."