XP 150 Problem

[Aqua_Flash]

I received an XP 150 that had a problem.

Basically what the problem was that when it was fully pumped it wouldn't fire, but when you pump it a bit or just with mostly air then it will fire. When I opened it the firing pin pulls back fine.

So this made me think the problem is with the pressure release valve. It basically has failed and will need taking out.

I have some pictures here as I don't fully know where the pressure release is on a XP 150.



I'm thinking it is the second vertical white part with a thicker centre that sticks out.



Or I'm thinking here as it could be that I have to seal up this part where the rubber black part sticks out, there are also small holes behind this part which made of think of possibly having to seal them off.

Any help appreciated. Thanks.

[Ben]

I'm fairly sure it's the one I marked as #3 in the attached image. #1 and #2 appear similar, so they're likely normal check valves. Judging by the orientation as well they'd have to be check valves because #1 leads from the reservoir to the pump, while #2 leads from the pump to the pressure chambers. #3 goes from the reservoir to the pressure chambers.

Looking at where the valves go seems to be a good way to identify them.

Again, no promises, but I'm fairly certain #3 is the valve to be removed.

Would you mind if we used this in our PRVD guide? It'll help people out.

After doing the PRVD modificaiton, be sure to count the number of pumps you put in your gun. If the pump gets hard, stop immediately and fire the gun. PRVD is dangerous on air pressure water guns because the pressure can climb too high very quickly, but it's acceptable if you know how many pumps the gun can handle and you count.

I do not know what the rubber stub part does, but I'd imagine it is necessary to let vent air into the XP 150's reservoir. There's no cap to put a vent into, so I suppose they put the vent in the internals.

[Aqua_Flash]

Thanks for the help. That makes sense, thanks.

You can use that picture for the article.

I'll update this when I have done the removal of the check valve, hopefully tomorrow.

[Ben]

Try putty epoxy. I really want to get a putty epoxy style guide to PRVD on our website. Though it'd also be great if you put it on your own website. As long as the guide is online and accessible, it's good. There is an old guide that uses putty epoxy linked from our guide, but it doesn't show what to do really, so it's not very useful.

Putty epoxy is a putty a lot like gum that comes in two parts. When mixed, they start to harden and will stick to nearly anything (there's a list on the package of what they'll stick to usually). It's used in plumbing repair all of the time and it's perfect for many modifications/repairs. Putty epoxy is superior to regular epoxy in things like this because it has a volume -- it can fill it the holes you cut better and it cures faster (some can cure in as little as 5 minutes!). My experience with it has been great, but I haven't disabled a PRV with it. Just roughen up the areas with sandpaper, but just use putty epoxy instead of regular epoxy.

[Silence]

Yep, #3 is the pressure release valve. #1 and #2 are the check valves; they're generally revealed by the fact that they're large, identical cylinders. And I agree, you've taken some really nice pictures! No blur and good lighting (the exact opposite of mine, when I get them). Thanks.

Honestly, though, I doubt plugging the pressure release valve will solve your problem. I'm not sure what type of trigger the XP 150 uses. If it's a pull valve, your trigger valve may be stuck closed. The problem is that the pressure itself acts on the plunger in the trigger valve, applying a force so large that you can't pull the plunger. If anything, a PRVD may aggravate the issue because it could let you raise the pressures even further.

EDIT: I might as well vouch for epoxy putty. Standard epoxy can probably provide a better bond in some cases, and you could use it to glue a stopped in place after removing the PRV. But you can scoop epoxy putty much more easily and use that as the stopper. Good advice, Ben.

[Ben]

Hmm, perhaps I should have read the post more closely. Does the firing valve open when pumped fully? If it does not, then disabling the PRV will not help. There's not much you can do for that problem aside from checking the alignment of the pins, pumping less, and pulling harder. Check this page for more information: http://www.sscentral.org/repairs/tri...ck_closed.html

Epoxy over a putty epoxy plug might help make that seal even better. Putty epoxy alone seems to work in the pressures we'll see in water guns though. But I can't see anything bad coming from using epoxy over putty epoxy.

[Aqua_Flash]

I'm actually starting to think that like what you said more may need to be done.

Everything is aligned properly, and the trigger pin pulls fine.

I'm actually starting to wonder if it is a faulty valve around the trigger area. I got this new, and barely used it, then gave it to someone who used it once and then that problem occurred. So it has developed very early on. Now I have it back I wanted to see if I could fix it.

When I have time, I might end up opening (or sawing open) the trigger valve to see what is going. Now because of this I'm not sure whether to disable the pressure release valve.

I've got a picture of the nozzle valve if it helps as well.



If worst comes to the worst, I might have to replace the valve fully when I have the time, but again I'm not fully sure yet.

[Silence]

I wouldn't open the valve quite yet.

Have you tried pumping and firing with the internals open? You've done the majority of the work for this test procedure since the water gun's already been taken apart. I would just pump and then pull the valve to see whether the parts move consistently, regardless of pressure.

[Ben]

Yeah, do some more tests to see if you notice anything wrong. The alignment looks fine as far as I can tell. There might be something in obvious need of repair if you open the valve, so try if you can't figure anything out. Be aware though that you will probably have trouble getting it back together unless you do some serious reinforcement like you did with your SS 300 gear too.

If it does come to valve replacement, please make a guide about that. There is my guide, but the way I did it probably only works in the CPS 2700, so different guides are necessary for different guns. Doing something SS 300 style should be worthwhile, in fact, it should be a good power modification.

[DX]

Putty epoxy held up in my 21Ks of old. It's very reliable stuff, as long as you mix it throughly and give it more time to set than the label says to.

Full valve replacement is tedious. Ben has done it [I did it to a CPS 1000 but never finished], but it is an annoying repair.

[Aqua_Flash]

Well the trigger valve is now open, and I have pictures.







From what I could see, I don't really know what to make of it. Everything looks fine. I think unless there is no other method then I'm rather tempted to do a valve replacement and do a write up.

Now I need to find a good place to put the valve if I happen to do this, as the tubing on the XP 150 internals is rather small. You can see from my other picture in my previous post that it is not too big. I could provide some more detailed pictures of the tubing if wanted to get a better idea.

[Ben]

Check the spring. Is it harder than you think it should be? This is just speculation, but I think the problem could be the combination of pressure and the force of the spring exceeding what you can apply with your trigger finger. If the spring hardens or something, then it might make pulling the trigger too difficult.

Another guess would be that the rubber seal is getting stuck inside or on the sealing face on the opposite end, but I don't think that's likely.

Valve replacement will be very different than what I did to my CPS 2700. A CPS 2700 is easier to repair because I could attach the tubing to a tubing barb. That's not the case here because the tubing is solid. Here my suggestion would be to cut the valve off right where it meets the tubing and find a small brass, copper, or plastic tube that fits over the XP 150's tube. That might be easier said than done, but with a variety of tubes available it's not impossible.

The easiest way to find a tube might be to measure the outer diameter with digital calibers and then check out McMaster-Carr for what tubes (if any) fit that. Also check the inner diameter to see if any pipes' outer diameter can fit in there.

Likely though, you won't be able to find a tube that fits perfectly, so my suggestion then would be to use putty epoxy and a copper coupler slightly larger than the tube. Fill in the space between the coupler and XP 150 tube with putty epoxy. Be sure to sand the inside of the coupler and the XP 150 tube with coarse sandpaper. Sand the outside too and use some regular epoxy after the putty epoxy has cured. After that you should be able to figure out how to attach a valve/nozzle to that end.

You will have to cut the case up to make the parts fit. I did that a bit on my CPS 2700, but since I was just sticking a pipe outside of the gun, not much cutting needed to be done.

As you can see, the valve replacement repair does involve a lot of decisions and it might seem tedious at times. But, once I got everything in front of me and I knew what to do, it didn't take very long, but it still was pretty involved. The most tedious part was cutting the case to fit the new parts because I would make a cut, test it out, make some more cuts, test, and repeat until it fit well.

[Aqua_Flash]

The spring is pretty normal.

Well I have decided to go through with the valve replacement pretty much now. Is this the right place that I have cut it? Or do I need to do it further down?



The good thing is that copper tubing and couplers are thankfully more common over in the UK, and my local hardware stores sell some copper and it is also easier to buy it online.

First to get a better idea on what sizes I'd need to get I'd like to know if the place I have cut is fine to start on it. Once this is cleared then I can start on getting the sizes.

Thanks.

[Ben]

That's fine. Where you cut doesn't matter as long as a pipe or coupler will fit over it.

It should be worthwhile to take the tube to the hardware store and see what fits over it. Measuring is okay, but knowing for sure is best.

[Silence]

Actually it's good that the best choice is already copper. Like brass, copper comes in size increments of 1/32", as well as various metric sizes. That should certainly give you a good choice of inner diameters. The right size tubing with epoxy (putty) should work well.

What type of valve do you plan on using? A ball valve? It should be fairly easy to use, even without a link to the trigger, since the front of the XP 150 is quite minimalist in design.