Question
I have a Rain Bird Professional ESP-8Si system.  Zone 2 (there are 8
zones)does not have enough pressure to fully extend the pop up sprinkler
heads and only has water flowing slowly from the heads.  Some heads have a
very low diameter spray pattern but most just bubble. (8 heads on zone 2)  All
other zones have appropriate spray patterns.  This is zone 2 but is the
farthest from the controller.  Thank you.

Answer
First check to make sure your valve flow control is open about halfway or a little more.  If no change, you may have a leak in the piping for that station somewhere.  Check for spots that are wetter than others, or greener.  Its also possible that there is an obstruction in the line somewhere.  These are hard to find, and require a lot of irrigation detective work.