Question
I went to turn on my sprinkler system this spring and the water near the turn on came flushing from the pipe rather than going through the lines.  I turned the valve on near my well tank in the basement and put the screw into the piping to turn on the system, then adjusted the small screws to send the water through the lines and not out of the piping, but continues to flow through the piping(another opening) rather than go through the lines.  What am I doing wrong?

Answer
It sounds as if you backflow preventor is what is dumping the water. It should have 2 valves on it. Try closing the valve going to the sprinkler system. Leave the one going to the house on. Now turn on the water. If the problem goes away, then slowly open the other valve.
This allow the backflow to adjust itself to the sprinkler system pressure.
Hope this is helpful

Matt