Each of my six zones works at approximately 75% pressure for the first 5-8 minutes, then eventually ramps up to the usual area coverage. Never did this before. I read an earlier post about low pressure in one zone and the recommended fix was either a new solenoid or diaphragm. I'm wondering if that could be the issue for me as well.
I have a Watermaster 57223 auto valve model. 3/4". Due to placement, I'd hate to have to replace the entire sprinkler valve.