Question
I have several Rainbird DVF valves in a system and they will not shut off unless I manually close them. I installed a system last year that uses rain water from my roof collected in storage tanks. It works with a pump relay wired to a Rainbird contol box. The pump was stonger than I thought so I have 3 valves hooked together to make a zone, I have 2 zones hooked up like this. When the controller starts a zone, both zones come on, the only way I can get a zone to not work is to manually shut the valves. I have; cleaned them, replaced the solenoid, replaced the entire upper portion (I did not replace the bottom part, it looks like no moving parts in there), re-wired them and even un-hooked all the wires completely out of the control panel and they continue to work when the pump comes on. I have checked the voltage at the controller and when it calls for a zone to come on, that zone is the only one that registers any current on a volt meter, the others do not show any current. I held a new valve in my hand and wired it directly into a new zone port on the controller and it comes on as it should (not sure if the valve should buzz the entire cycle time or if it should only buzz as it opens and closes though, it buzzed the entire time) The system worked fine last year and at the begining of this season. The only thing I have done different was activate a valve that was installed at the same time as the others but was not being used. When I first started it up, it ran with both zones even though it was only wired with one of them, shortly afterwards, I noticed another valve doing the same thing and soon after, all of them were doing it. I have un-wired this zone but it did not fix the problem.
Sorry for the long email but I have tried everything I can think of.

Answer
Hey Len, I hope this helps. From what you're telling me, No matter if the valve is hooked to the controller or not, the valves are running water through them, as soon as you get water pressure to them. There is a few things to check, and it sounds like you might have already did these things, but let me go through them with you. It sounds as though you replaced the solenoid, and it did no good. The other thing about the solenoids, is that they need to be tightened clockwise all the way down, until they're tight. If the solenoid is turned counter-clockwise, just about a 1/4 turn, the valve will operate manually. Just make sure the solenoids are tight. When you took the top of the valve off, the rubber piece is called a diaphram, did you replace the diaphram? Also, if the pressure is too high, it could compress the rubber seat on the diaphram and make it out of round, not allowing it to seat properly at the bottom of the valve body. Just check to make sure the diaphrams are okay, and that they don't have any imperfections, or tears in the rubber. The other place to check, while you have the diaphram out, is at the very bottom of the valve body. You will notice a cylinder shape in the plastic at the bottom of the valve, this is where the diaphram seats on the valve body, to stop the flow of water. Feel around this piece with  your fingers, or visually inspect the seat, to make sure there are no cracks or imperfections. If this seat is cracked, the valve will never shut off properly. It sounds as if the diaphrams are either going bad, or the seats in the plastic are cracking on you because of the pressure. Let me know if I can be of further assistance, thanks and have a great day.