Question
We prepared our backyard for grass. Brought in dirt and tested the existing sprinkler system- all was fine coverage good. All I've done since then and installation of sod is to raise the height of  riser on 3 head. Now its like I have very little water pressure- on 1/2 the heads are up and  even they are only about 1/2 up. ANy ideas?

Answer
Hey Dean, I hope this helps. I would suspect that either you have a leak in one of the pipes, or one of the risers or heads is leaking. Or it could be the diaphram in the valve is going bad, and the valve is not opening up all the way. If you have a leak, with the system on, look for any areas that have a lot of water in them, this could indicate a break. If its the diaphram, sometimes you can tell, by listening to the valve, and hearing a restriction. Or if it has a bleed screw on the valve, if it opens fully when the bleed screw is opened, but not when the controller opens it, then it is the diaphram. A good web site to learn how to replace a diaphram is: www.irrigationtutorials.com. Good luck and have a great day.