I recently added a short extension, riser and fitting to an old 1" pvc line I haven't used in several years. But there doesn't seem to be enough pressure to make the fitting work correctly (and I've tried several heads). Water just dribbles out the head. When I remove the entire head assembly, water will shoot out the open line a foot or two. I can easily stop the flow with my thumb and when I release it the pressure returns after a second or two. Does this suggest the problem could be a leak somewhere along the line? Or a blockage, maybe? Or could it be a problem with the valve?

This is the only head on the whole zone, it's not particularly far from the valve and the level of the head is lower in elevation than where the feed comes off the main water line to the house (if that makes a difference).

I'm not sure what to do next, other than just cut a new line in after the valve out to where I want the sprinkler head. That assumes the problem is somewhere in the line underground. It's so old, deep and covered with plants that it would actually be easier just to run an entirely new line rather than try to dig up the old one. But before I do all that I wanted to make sure it couldn't be something else, like a bad valve.

Any help is much appreciated.

City water of a pump" Do you have a pressure gage that you can check, both the pressure at the head and for a leak in the line? To check for a leak put the gage where the head goes and then close the feeder valve. If the gage falls to zero then you have a leak. Good luck. Tom