I have a 2000/45m schwing,been having some issues intermittent.my volume control works when it wants to most of the time it is fine and then it decides to speed up on its own.

any ideas?

what pumpkit is on the truck?

yah the system has got trash in it. got to take apart and clean it out

Kneerick, The volume control uses pressure from the accumulator circuit to regulate the strokes. The more pressure that is allowed to go to the main pumps destroke them. No pressure allows the pumps to go to maximum volume. If something like trash is in the regulator, ( piece of o-ring or metal from pump), the flow to the pumps will be resticted and hence the wide-open speed of the pumps. Clean out the regulator and the manual stroke selector.

Also check the electrical connection to the solenoid for pump speed, usually located near your hand valves. If it is corroded or loose, no power to it allows the pumps to stroke at maximum, more electrical power to it destrokes the pumps.

I'm with CVic, but before you start taking everything apart, check your MY pressure, see what happens when it is acting up (you can check that by pumping water in reverse, dont have to be on the job); more than likely you have to replace the cartridge for the electrical stroke limiter, you cant repair those;keep us updated