WaterWar.net

my 300 is able to fire and pump but needs some work all the same, here's why.

1. The first check valve keeps closing late
2. Because of the water warriors tank caps (I was tired getting my back soaked by my own blaster), the air bipass kicks in even when trying to pump water
3. Damaged lever (I plan to use a screw to fix it)

It's a shame we can't just get together and look over this in a machine shop, or at least someone's garage with lots of tools and a good camera. Would be a lot easier to fix if we could examine everything.

-First check valve, so the intake valve for the pump? Does that mean that when you pump some of the water goes back into the hose/backpack?
-Air bypass? The tank caps should let air in to prevent negative pressure
-Pictures?

Yes that check valve soakinator, and the reason that the air bypass is kicking in is because of the increased resistance in drawing the pump.

When you say air bypass, do you mean the check valves in the tank caps that draw air into the reservoir during pumping?

Clearly no one knows what an air bypass is so I will tell you all.

The super soaker 300 (and I think the CPS 3000) have a ball valve on the hose connection that blocks water from reaching the pump, a spring activated check valve hear allows air in at this time. My 300 with water warriors caps on the tank has a draw resistance high enough that it opens with the ball valve open.

It's a feature that lets you replace your pre-charge should you happen to mist shoot, without having to unload. Nice eh?

That is an interesting feature for the SS300... basically ensuring that you will have enough air pressure... but it would make no sense on the CPS 3000.
Also, the air bypass valve on my SS 300 leaks like crazy and is of no use to me at all. I almost filled in it with epoxy a few years ago, when I made a thread about it...
Annd the SS 300 backpack caps don't have a valve, just a hole in each cap to let air (and water) through. Seems crazy right, but that's just the way it is.

A photo of it maybe?

It's a new one on me. My guess is that it does the same job as the air vent in your backpacks (basically a PRV). Obviously if you pump with the backpack valve shut you're going to create some pretty large negative gauge pressures pretty quickly (very little volume between the backpack's ball valve and the first check valve). If so then it's a feature designed to stop you breaking your blaster if you pump it with the ball valve shut (which would also explain why you may have seen one on the CPS 3000) and not primarily a pre-charge inlet (although it seems to be a useful side effect).

Essentially the source of your problem is you've got the wrong caps on. Either switch back or, if it is a check valve and not just a leaky connection, you could try adding a stronger spring (which would unfortunately also reduce it's effectiveness as a pre-charge inlet) or just disable it completely.

I think the valve works the same as a reservoir cap check valve, at least on my 300 it does. It basically switches the input from the pump from the backpack water to open air.