WaterWar.net

Is there a general dowel for pump rod reinreinforcement/repair?

Nope.
Different guns have different pump diameters. Don't ever use a wooden dowel rod, they shrink, they expand, they rot and they break. Use some PVC or aluminum pipe.

Off the top of my head, the size is between 3/8 and 1/2 inch for most pumps.

A lot of blasters use roughly 3/8" ID and 1/2" OD plastic rods.

My advice is just to take your pump to a hardware store and get some one to help you find something that will plug it.

Umm I had a CPS 1000 that was missing the pump, I guess you could walk into a hardware store with THAT and ask for help?

What would be nice is a bolt, with two large washers and one smaller diameter washer the same thickness as an o-ring, then you can sandwich the smaller washer and o-ring between the other two. Thread/glue that bolt into a piece of pipe and you're done. In theory.

In practice you start with an o ring, and then from there find a way to secure it on a pipe between two things that won't slide and won't let the o ring come off unless you pull the pump out.

The thread I wrote on homemade pumps should help, but the CPS 1000 may have a slightly different pump diameter.