How do I fix in-ground sprinklers that pulse on and off?

Question

I have 9 zones. 4 of the zones are functioning fine. The other zones, when activated, send the sprinkler heads up and down rapidly. This causes problems with the rest of the plumbing in the house. I have found the control valves for these zones and I can hear the valve pulsing on and off. Furthermore, I can manually turn the valve with my hand to turn it on and off and send water to the sprinklers in each zone.

I have changed a solenoid at one of the zones, and nothing changed, it is still misfiring.

I have also switched wires at the control box, but the same control valves all misfire.

Any suggestions?

Answer 1

wow... neat.

i would disconnect the wires, and meter them with the zone on.  watch your voltmeter to see if perhaps it's your main control box cycling the zone.  you should see a constant fluctuation in the voltage, causing your solenoid to do just what it's told.  switching wires won't change anything if that zone is being told to cycle like that.

try this and edit with an update!

EDIT:   I would check the voltage at the box, where the wires to each zone connect.  check the voltage when the zones are each turned on.

i'm in the process of double-checking, but i was pretty sure you were supposed to have 24 volts to each solenoid, as you get a hefty shock if you touch one of those wires.

also, did you check from one lead to the other?  or did you check from the hot to ground?  voltmeters measure differential, so you might be seeing the power each solenoid is using up.  if you put your leads on 2 hots, you will get a reading of 0 volts, even if there's 120 on each.  Update!

Answer 2

Sounds like a wiring issue, but it could be a bad/dirty diaphragm inside the valve.  Check the wire nut junctions - do they look clean and tight, or are they corroded/loose?   If the junctions are good, try swapping the control wires between a good valve and a bad valve.  If the problem moves with the wiring, you've got either bad wiring between the valves and the box, or a failing timer.  If the problem stays with the valve, open it up and check the diaphragm.