Found out what it was today. First two valves off the header weren't closing all the way. Shut them off with the flow control knobs and the system is working. Will replace the valves tomorrow since the diaphragms are almost as much as a new valve. Going to add a ball valve upstream of each solenoidal valve when i have the time.
I bought this house with the sprinkler system winterized. Spring came, and I started up the system. I have irrigation water coming from 3 large pumps along with a few other small farm houses. The main is 1.5" and comes through a meter. The meter is 100% open and then steps down to 1" and goes into a vacuum breaker. I tested the breaker and I have good pressure on both legs. It then goes into a master valve (1" orbit w/ flow control) and then into a 1.5" poly header that runs about 500 feet (don'...