Question
I have a Toro sprinkler system with 5 zones.  I just did my spring start up and zone two will not work however the other four zones do.  I checked the valve and can hear water flowing, I also took off the solenoid and found that it is also working.  There are four heads on the zone and all of them have water bubbling out of the tops but not enough pressure to get them to pop up at all.  I had the system blown out prior to winter and none of the heads are near the street where a plow could have damaged them...What is going on????

Answer
Make sure that the flow control for the valve is opened about halfway or a little more.  If this doesnt work, you may have to dissemble the valve and service it.  Check out this link for a good tutorial on how to do it.

http://www.irrigationtutorials.com/faq/repair-valve.htm