hello, my old hardie sprinkler not working , water only spraying moderately even though I turn on my tap full blast. What is the cause, do I need to dig out the sprinkler head and replace it? Are there any simple fix to that?
You have a blockage/restriction in the line somewhere, between that head and the supply end.
If you have some fencing wire or something like it, try feeding that down the line towards the supply end.
One question, do you have a filter in the line that feeds these sprinklers?
If not, look at installing one, it will minimise things like this happening in the future.
It's great that you've received fantastic advice from @MikeTNZ and @robchin. You could try a popup head test. If you have a similar popup sprinkler remove the head and test the faulty one on that assembly. If the head does not pop up it could be a faulty O-ring or the pop-up head getting caught on something. However if the working pop-up head doesn't work when you tested it on the other side, then there is definitely something blocking the pipe and is reducing the pressure to that assembly.
Please keep us updated with your project, we look forward to seeing your sprinkler repaired.
If you need further assistance, please let us know.