Low pressure in one zone.

[Burleybutt]

Howdy, this is my first post. Sprinkler systems are a new thing to me and I would appreciate some help. I have an 11 yr. old Hunter System with 3 zones. One of the zones developed low pressure and some of the heads don't work at all. I tried digging out a few sprinklers to clean them but it didn't help. I can hear a knocking noise but can't isolate it. There are two valve boxes in the ground, I assume one for each zone. I've read that solenoids can be a cause for low pressure rather than clogged lines. Are they located in the zone boxes, and if so, should I be looking at replacing them? Any help will be greatly appreciated. I live in Texas and my lawn is burning up. Thanks!

[mike1059]

The solenoid is located on the downstreem side ot valve. On a hunter valve it will be round and sticking up from the top of the valve. If you turn each solenoid counter-clockwise to open the valve you will know wich zone it is and if the low pressure zone comes on at full pressure the solenoid is bad and needs to be replaced. If the zone is still at low pressure open the flow control knob in the center of the valve.

[Burleybutt]

After doing some research I checked the soleniod in the low pressure zone and found it to be faulty. Good thing I also bought a diaphram because the water was still running when shut off. Put in a new diaphram and problem is solved. Thanks Mike.