Hey guys... I've been troubleshooting my irrigation. I found Zone 5 to have low pressure. The sprinkler heads aren't coming out all the way and I can easily push them back down with my finger when the zone is on.

The valves I have do not have flow control - it has a manual bleed screw.

So, I went to the valve box and I noticed right away Zone 5 is much noisier than the other zones.

I swapped solenoids and that didn't help. So then I took out the diaphragm all together. When I turned the supply back on, water went out to Zone 5 (obviously) and this time, you can see the spray is coming out with much much more pressure. So I was glad it was not a cracked line and it likely has something to do with the valve.

My main suspect right now is the diaphragm, but I realize it may still not be the culprit. Regardless I have a replacement diaphragm in order.

What I don't understand is how can it be the diaphragm based on what I've learned about how valves work is this.

If the equalization hole is plugged or malfunctioning (diaphragm), then the valve will tend to stay open and the sprinklers will leak or keep running.

In my case, it seems like the diaphragm is not opening all the way and ends up restricting water flow. So that leads me to believe it has to do with the orifice and solenoid. But I've already swapped solenoids with another zone (that seems to be fine - it certainly is not noisy like zone 5 and the heads on that zone seems to have good pressure). So if it's not the solenoid, then it must be the orifice - if water is not escaping fast enough through the orifice (even with the solenoid open), that would keep the diaphragm from opening all the way, right?

Here's what I've observed also. When I open up the bleed screw, the pressure at the heads go up (and the valve gets quieter). So this leads me to believe the diaphragm is capable of opening all the way if enough water is allowed to escape from the top chamber.

Could it be the orifice? If it is and I can't get it unclogged, that would mean a new valve altogether - which would be an ordeal to replace.

Or could it still be the solenoid? May just buy a new solenoid to be absolutely sure?

How else can I test?