I have been trouble shooting a system and can not seem to figure out what is wrong; I think it may be a leak but, could it be the valve? I have checked and verified that the water is on at each cut off. zone one, mp rotators, 8.5 gpm, rain bird 100-DVF-SS: 1"; this zone works sometimes, when it does work it takes 4-5 minutes to build up enough pressure to work, all mp's pop up. When I turn zone off and try to turn it on again, nothing happens but water running out of sprinklers. zone two, works great. zone three, works great. Any and all help is appreciated!