Yard sprinkler problem

Have 1 sprinkler head that does not work.
I have removed the sprinkler unit form the housing, which in theory, should allow water to gush from the line.
No water escapes when the rest of the yard is being watered.
It "appears" that this particular head is the next to last on the line. What appears to be the last head on the line is getting water.
Dont know where the lines are, as system was installed several occupants back.
Can anyone suggest a way to locate underground plastic pipe.
And, a way to clear the head I already know is plugged?
Have 60 gal/5hp compressor and enough hose to reach anywhere in the yard.
thanks
gary
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On Monday, May 29, 2017 at 3:05:12 PM UTC-4, Gary wrote:

I would try connecting a water hose to the non working sprinkler and try to back flush. You might remove the sprinkler head from the " last " outlet.
I am assuming that the one sprinker head has worked since you bought the house.
If it has never worked since you bought the house there are all kinds of possibilities. Like the water was not drained and the pipe froze and broke. And then the owner did some micky mouse repair and jost used a hose to water that part of the lawn.
You could run a wire inside the plastic pipe and connect a signal generator to it and trace with a portable radio.
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Where would I buy one of these?
thanks
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On 6/2/2017 8:51 AM, Gary wrote:

Google "wire tracer"
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No, it should release water in a measured stream at measured angles.

Have you left the water turned on and prodded with a long drill bit (without drill motor) after removing the head? If something is blocking the junction, it still may allow water by to feed the end head. I've seen meeces in systems left open overnight.

Most are perimeter. Use a flat shovel to get the grass off the top and a trowel to get down to the pipe to find the direction.

Borrow your neighbor's ground penetrating radar unit. If it's in use, grab your shovel (as stated above.)

Did you swap the two heads to make sure the one is, indeed, plugged. When I pull a plugged head and no water comes out, I tend to think the problem is elsewhere. After I get water out the pipe, then I check the head.

The pop-up heads with water-fed rotation can be hard to clean, but sometimes it's just a matter of feeding water backwards through it. Water works better than air, but air can work, too. Before pressurizing it, extend it so it doesn't explode when pressurized. Try 40psi.
I've seen more people allow clods of dirt into open irrigation pipes when they were servicing them than any other mistake. Silt is usually self-clearing, but moss and sand can be troublesome.
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This sounds pretty interesting, Would you happen to recall the Harbor Freight SKU #for this item?
thanks
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Sure! Here ya go: http://tinyurl.com/yaxlv2t2 and http://tinyurl.com/yakc8kts A better unit: http://tinyurl.com/y9pasxup (all googled so ask no deeper questions, please)
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