CPS 1200 Pump Problem

Repairs to water guns. Please put repair topics in this forum so that people do not have to sort through so many topics when looking for a repair. If a fix is included in the topic, please add (Fixed) before the topic title to indicate so.
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Spinaziesoep
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Joined: Mon May 17, 2010 9:27 am

CPS 1200 Pump Problem

Post by Spinaziesoep » Thu May 20, 2010 8:56 am

Greetings everyone, I'm new to these forums, but found lots of useful information in them. One thing I couldn't find however, is if there's a way to repair a poorly performing pump on a CPS 1200. It runs stiffly, and it makes slight gurgling noises when being extended, even when the reservoir is completely full. It pumps in air together with water, causing mist shots and reducing performance.

I recently bought a used CPS 1200 (not sure if it's mark 3 or 4, it has the grey-purple colour scheme). It still performs nicely, except for the pump. When I just bought the gun the pump was extremely stiff, it was almost immovable, and it pumped in air besides water. Inserting vaseline lubricant and later silicone lubricant fixed things somewhat, though it still ran stiffly. After some careful usage the pump runs better now, but it still has the regular habit of sucking in both air and water, which causes major mist shots, and decreases output and range. When extending the pump it makes a slight gurgling sound, no matter how full the reservoir is. According to measurements from iSoaker and SSCentral the pump volume is supposed to be 31-35 mL, but the pump barely manages 20 mL when pumping at full speed. When pumping really slowly the pump volume increases to about 25 mL, but that of course is out of the question on the battlefield. I also tested if perhaps the pressure safety valve was overreacting, thereby reducing pump volume, but this was not the case, the valve works fine. It's purely the pump malfunctioning when sucking in water.

Is this a common problem? Is there a relatively easy way to solve it? Other than the pump the gun is in surprisingly fine condition and works like a charm, so I'd really rather not open it. I have very little experience and tools available to open water guns, and the I read the CPS 1200 model is quite difficult to open without causing visual damage. Help is very much appreciated. :)

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cantab
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Joined: Fri Oct 19, 2007 1:35 pm

Re: CPS 1200 Pump Problem

Post by cantab » Thu May 20, 2010 4:41 pm

A few possibilities spring to mind:

A leak in the piping to the pump (you would expect water leaking out if this was the case).

A poor seal in the pump itself (maybe most likely).

A defective check valve (not sure if this would produce the described symptoms).

If it's the seal, you may be able to replace the O-rings.
I work on Windows. My toolbox is Linux.
Arsenal:
Super Soaker: XP215, 2xXP220, Liquidator, Aquashock Secret Strike M(odded), Arctic Blast M, CPS1200, CPS2100, SC Power Pak, 3l aquapack, 1.5l aquapack
Water Warriors: Jet, Sting Ray M, Shark, Argon M, Tiger Shark, PulseMaster
Others: Waterbolt, The Blaster, Storm 500, Shield Blaster 2000, generic PR gun, generic backpack piston pumper (broken), 3l garden sprayer M, 10l water carrier:

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Spinaziesoep
Posts: 4
Joined: Mon May 17, 2010 9:27 am

Re: CPS 1200 Pump Problem

Post by Spinaziesoep » Thu May 20, 2010 10:37 pm

cantab wrote:A few possibilities spring to mind:

A leak in the piping to the pump (you would expect water leaking out if this was the case).

A poor seal in the pump itself (maybe most likely).

A defective check valve (not sure if this would produce the described symptoms).

If it's the seal, you may be able to replace the O-rings.
Thank you for the reply. It is most certainly not a leak in the piping, as the gun does not leak any water whatsoever (besides the normal 'after leaking' after unloading a shot). I am also quite certain that the security valve is not defective, as the gurgling sound only occurs while extending the pump, not when contracting it. If it's a poor seal, I guess there is little choice for me but to open the gun and fix it. Hopefully it won't be too difficult. I'll be sure to post back here once the problem is identified and (hopefully) taken care of. Cheers. :)

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cantab
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Joined: Fri Oct 19, 2007 1:35 pm

Re: CPS 1200 Pump Problem

Post by cantab » Thu May 20, 2010 10:58 pm

If the "out" check valve from the pump is defective, then when extending the pump fluid (either water or air depending on what is present) will be drawn out of the pressure chamber and tubing leading to the nozzle, as well as out of the reservoir. Dunno if that would cause gurgling though. If it did, you might expect the noise to be most in the first pumps, and diminish as the pressure chamber and tubing is filled with water by subsequent pumps.
I work on Windows. My toolbox is Linux.
Arsenal:
Super Soaker: XP215, 2xXP220, Liquidator, Aquashock Secret Strike M(odded), Arctic Blast M, CPS1200, CPS2100, SC Power Pak, 3l aquapack, 1.5l aquapack
Water Warriors: Jet, Sting Ray M, Shark, Argon M, Tiger Shark, PulseMaster
Others: Waterbolt, The Blaster, Storm 500, Shield Blaster 2000, generic PR gun, generic backpack piston pumper (broken), 3l garden sprayer M, 10l water carrier:

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C-A_99
Posts: 1502
Joined: Tue Aug 01, 2006 11:09 pm

Re: CPS 1200 Pump Problem

Post by C-A_99 » Fri May 21, 2010 4:04 am

The CPS1200 does not use O-rings but instead uses a special seal used for water gun pumps. That part is the least likely to have a problem in my experience, but another possibility is that there may be a leak in the connection of the pump rod to the seal itself. Make sure the screw that's deep inside the pump rod is tight but if that doesn't fix any leak there, epoxy may be needed.

A likely symptom of air getting mixed with the pump is that the pump rod will "bounce" when trying to pump, making pumping a bit more difficult and a lot more annoying. If this is a problem, then it's likely that the pump seal isn't attached to the rod properly, as I mentioend above.

I can't think of anything else at the momeny that may be causing problems.

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