Question
QUESTION: My sprinkler system suddenly stops working as it used to. The system is from Intermnatic Cooperation. I have four zones and when the system is running none of the heads pop up to water the lawn but water gushes out of the backflow preventer.
    The backflow preventer, which I suspect is the fourth piece of pipe into the ground, was broken off by a lawn mower more than a year ago. The system still worked after that, both automatically and manually, and water gushes from that broken pipe at the end of each zone. Recently, the heads do not pop up at all but water keeps gushing from the backflow the entire run of all zones.
    The fact that water is gushing out of the backflow when the system is on to me, is indicating that it is trying to run but something is preventing the heads from popping up.
    I am hoping this is something I can fix myself without having to spend a lot of money. Already I am frustrated with a plumber I called and is giving me the run-around. I suspect he cannot fix the problem and before he comes and causes a bigger problem I am doing some trouble shooting myself. I have no experience with irrigation problem but I am very intelligent and good with tools and instructions.
    I'd be happy if you can help me.

ANSWER: Hi
looks like you are talking about the index valve not the back flow preventer
the backflow is located before the index valve.  The ones who has 4 pipes is the index. The backflow could be electrical and in this situation has a selenoid and a couple of wires to the timer, could be hydraulic and is a vacuum breaker and has no wires. The index valve is roudd shaped and has 4 or more pipes going into the ground. Appears your system has 3 zones and one blind oulet and this was broken. If our sprinklers does not pop up, you have the index clogged. In this case you can open it and clean if necessary replace the disk esteem.  
Regards
Guillermo

---------- FOLLOW-UP ----------

QUESTION: Some additional clarification may shed more light on the problem. Looking at the sprinkler "head" there are four pipes that go into the ground. When water was gushing out from the piece broken off I decided to dig into the ground and see what was going on there. The three other pieces of pipe are securely connected underground, no leakage observed. One of the three pipes was split into two so there were four pipes running under ground, and a smaller black piping which I suspect is the electrical part of the system
   So I really have four zones but that fourth piece of pipe that was attached to the head - top part, because the head has opening for four pipes, was for what? a blind outlet? So you are suggesting I unscrew that round top off and clean that out? Is that where the disk esteem is and if it needs replacement where can I get that to buy? While I am doing this do you suggest I replace the blind outlet that is broken off, and also shut off the water main before I begin the project.

Thanks.

Answer
Yes Alma,
you have 3 zones on the valve. You can check it reading the number on the valve top if it is a K4000 or if it is a fimco looking a the highest number at the cam (top).
if it is a krain you can find the parts at any sprinklers store. If it is a fimco find it at home depot. By the way you can find valuable information at www.irrigationtutorials.com.
if you can provide me with a little more details like valve brand, timer brand. Kind of backflow preventer i will be more useful to you.
Regards
Guillermo