Question
My husband installed a new Rainbird system. He checked the PSI and it was 80. When testing the sprinklers, there doesn't seem to be enough pressure to pop up the sprinkler heads more than 1/2 way.

Answer
Make sure the main valve and the irrigation valves are open.  Another consideration is that the amount of water being used by the system needs to be less than the amount supplied.  This is the gallons per minute or GPM.  If there are too many sprinklers on a station, the demand for water will be more than the supply, and the heads will not function well.