[Guide] Fix slow pumping in CPS guns due to manufacturing inconsistencies

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Joined: Thu Jul 26, 2018 8:46 pm

[Guide] Fix slow pumping in CPS guns due to manufacturing inconsistencies

Post by AmaIro18 » Mon Sep 03, 2018 12:35 am

Hello guys.

For the longest time I have been trying to fix an issue with my CPS 2000. The issue is the same issue that I tried posting about here. I have a CPS 2500 and a CPS 2000, and they basically have the same internals, so I was trying to figure out what was wrong with my 2000. Basically, the problem is that when I extend the pump towards the nozzle, I had to wait a little bit for water to get past the first check valve (the check valve between the reservoir and the pump). If I didn't wait, no water would be in the pump area, and thus no water would be pushed into the chamber when the pump is retracted.

At first I thought it was a problem with that first check valve. Recently though, I used a long screwdriver to push the check valve from the reservoir intake, and compared the force necessary to open my 2500's check valve to my 2000's check valve. Strangely, they seemed the same. So I started to think that perhaps the problem wasn't the check valve.

Then, I stumbled onto something:


My 2500 reservoir (in the red) had an opening much bigger than my 2000 (in purple). I thought I should try widening the intake opening, but before I did anything permanent, I first wanted to make sure and attached the 2000's tubing system to a water bottle using thread tape. I pumped as fast as I could and lo and behold, I was able to pump as fast as possible without having to wait.

After I confirmed that the bottleneck was actually the small opening in my 2000's reservoir, I drilled the opening much wider, using a 5/16" drill bit. I did this to both reservoirs. Below is a pic of the resulting 2500 reservoir:


And with that, my pump issues were all gone, I could pump my 2000 as fast as I wanted with no issue.

This seems to be a manufacturing inconsistency, some CPS guns might have this problem, some might not. Not sure if this was a known issue, but I figured I'd post this here, considering this issue with my 2000 has been plaguing my existence for the past two months.

If anyone runs into the same issue that I described, take a look at the opening at the reservoir on your gun. I'd suggest testing with a water bottle like I did to be on the safe side before drilling so that you're absolutely sure, but at the very least be careful when drilling. Remember, these guns are old and most likely won't be produced again, so we should try to take care of the ones we have. One last thing, don't forget to rinse the reservoir! You wouldn't want bits of plastic getting into the valves/tubing/pressure chamber!

Last edited by AmaIro18 on Sat Sep 08, 2018 10:20 am, edited 2 times in total.

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Re: [Guide] Fix slow pumping in CPS guns due to manufacturing inconsistencies

Post by SSCBen » Mon Sep 03, 2018 10:11 am

Very nice find. I don't recall seeing this sort of fix before.

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Re: [Guide] Fix slow pumping in CPS guns due to manufacturing inconsistencies

Post by soakinader » Mon Sep 03, 2018 11:30 pm

I second that. Nice find, probably a rare issue but I'm sure at some point this will help someone.
My friends call me Nader. My foes just run.
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I find 'em, I fix 'em.

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