Max-D 5000 Pump Problem

[Gold Hawk]

I have an itty bitty problem with my teammate Eric's Max-D 5000.

When you pump it, the pump slides very, very loosely, and it does not pressurize at all.

I opened it up, and checked it out today, and I can't find out what is going on with it.

Can anyone help me?

-Gold

[Drenchenator]

I can see one of several things wrong: a check valve is broken, the pump seal is bad, or the relief valve functions too early. Does it leak at all? If not, then it is either a broken check valve or relief valve, and both are major problems.

If the check valve is broken, it will be the input one--the one closest to the reservoir. When the pump moves, no pressure is created because the water can flow back into the reservoir. The only thing you can do in this case is order a new one or make a new one.

If the relief valve is broken, it may be best to remove it. Simple as that.

But I'm unsure which problem the gun has; in both cases the symptoms seem much the same--if you open the gun, both cases will appear identical. I can think of a simple test though which should tell if the input check valve is broken. Open the gun and remove the pump and valve assembly. Take out the pump rod and pour water down the shaft itself. If it fills, that means that the input check valve isn't broken. If water flows through, it is.

[Gold Hawk]

Originally Posted by Drenchenator

I can see one of several things wrong: a check valve is broken, the pump seal is bad, or the relief valve functions too early. Does it leak at all? If not, then it is either a broken check valve or relief valve, and both are major problems.

If the check valve is broken, it will be the input one--the one closest to the reservoir. When the pump moves, no pressure is created because the water can flow back into the reservoir. The only thing you can do in this case is order a new one or make a new one.

If the relief valve is broken, it may be best to remove it. Simple as that.

But I'm unsure which problem the gun has; in both cases the symptoms seem much the same--if you open the gun, both cases will appear identical. I can think of a simple test though which should tell if the input check valve is broken. Open the gun and remove the pump and valve assembly. Take out the pump rod and pour water down the shaft itself. If it fills, that means that the input check valve isn't broken. If water flows through, it is.

Thank god, it filled.

So you're saying I need to either remove the relief valve, or I need to fix the pump seal.

How would I go about fixing the latter?

[Silence]

There's a problem here. The Max-D 5000 is a pressurized reservoir water gun. In standard soakers, pumping moves water from a reservoir to a pressure chamber that is filled with air beforehand. The presence of the water in the chamber compresses that air, generating pressure, and the air pushes back on the water when you shoot.

In pressurized reservoir soakers, there's only one tank, not two. You fill it with water, just like a reservoir. But pumping forces air into the tank.

The problem still lies with either the pressure release valve or with the check valve, though. You can still fill the pump with water to see if anything squirts out of the check valve. Depending on the location of the pressure release valve, the method might even work for that. But if the PRV release excess air directly from the reservoir, and not from the pump, then there's a problem: pumping is going to put water into the reservoir (since the pump's been filled) and release air instead.

Ask if there's any confusion about how the systems work. The different types of water guns can cause confusion, especially given all the terminology.

Anyway, I hope you get the problem fixed!

[Ben]

Another problem not mentioned is that the cap might not be tight enough or on at all. Check the cap.

[Drenchenator]

There's a problem here. The Max-D 5000 is a pressurized reservoir water gun. In standard soakers, pumping moves water from a reservoir to a pressure chamber that is filled with air beforehand. The presence of the water in the chamber compresses that air, generating pressure, and the air pushes back on the water when you shoot.

In pressurized reservoir soakers, there's only one tank, not two. You fill it with water, just like a reservoir. But pumping forces air into the tank.

Oops, I guess I didn't know that. It doesn't help that it has a fake pressure chamber then. Either way, the problem could be one of the two things I said before.

[Gold Hawk]

Is there supposed to be a rubber thing on the end of the Max-D 5000's pump stick?

If there is, that could very well be the problem.

There was nothing in the pump shaft when I looked.

Woah.

-Gold

[Ben]

Yep, that means the pump seal is bad (or in this case missing), so that would be the problem.

From what I know, Max-D water guns use simple rubber O-rings as their pump seals. Take a picture of the end of the pump seal and post it here if you don't think it uses O-rings. The basic #9 O-ring likely will fit. All you have to do is repair then is visit a hardware of home improvement store and look for some #9 O-rings. Here's a picture of what the container should look like: http://images.sscentral.org/aphparts/12.jpg

[Silence]

Wow, thank goodness you made the discovery. I can't believe we didn't think of that. I guess CA-99 pointed it out at iSoaker.net.

There are numerous guides to making your own pump:
Drenchenator's
m15399
Ben's APH article

[Gold Hawk]

Originally Posted by Ben

Another problem not mentioned is that the cap might not be tight enough or on at all. Check the cap.

Funny you should mention that, cause an old team member had a Max-D 5000, and he though it was busted. Turned out the cap wasn't on right.

But the trigger wasn't very strong cause he had left it outside for 3-years, and the trigger broke.

But I checked the cap on this one.

I think it's just the O-ring that is the problem.

-Gold

[Gold Hawk]

Originally Posted by Ben

Yep, that means the pump seal is bad (or in this case missing), so that would be the problem.

From what I know, Max-D water guns use simple rubber O-rings as their pump seals. Take a picture of the end of the pump seal and post it here if you don't think it uses O-rings. The basic #9 O-ring likely will fit. All you have to do is repair then is visit a hardware of home improvement store and look for some #9 O-rings. Here's a picture of what the container should look like: http://images.sscentral.org/aphparts/12.jpg

I've got the O-ring, what do I do to attach it?

-Gold

[Silence]

You may not have seen my post (after Ben's)...try refreshing the page. I linked to a few pump guides that show how to use an O-ring for the seal on the pump.

In your case, you could just put the O-ring on the end of the rod and wrap electrical tape or duct tape on each side of it to prevent it from sliding.

[Gold Hawk]

This can be closed. I fixed it and it works fine.

-Gold