Do you know why the yard sprinklers pulsate when turned on for around 1 minute

Question

Its after the pressure regulator!

Answer 1

The sprinklers rotate using water pressure.  the pressure does not maintain enough force to turn the sprinkler head until all the air is out of the line.  At that time the pulsating stops and the head starts to rotate.

Answer 2

Could be the heads are dirty and air is in the line, It may take a little time to purge, as long as it work the rest of the way, then don't worry. It will be ok!

Answer 3

Air pockets in the lines.