Question
We bought a house in western colorado with an existing, old, poorly maintained in-ground irrigation system.  Pressures have been too low for complete coverage, and the lawn is baking in places.  The pressure isn.t terrible, but when we try to water the bare spots with a single hose bib and a standard wand sprinkler, the pressue decreases over 2-3 minutes until it is almost zero.  Is this an inherent problem with these systems, or would a new pump power a single wand sprinkler?  (We do plan to landscape the property and replace the entire system at some point).

Answer
Chris,
It is more of an inherent problem in Colorado. You guys ain't got no water up there. I've never been to the Rocky Mountain State and I know it must be lovely, but I sat in a class given by somethone called an irrigation auditor who worked for the state(?) of Colorado. I know water is at a premium there. Nevertheless, I assume the pump is a well pump that supplies the home as well as the irrigation. It sounds like you are sucking the well dry after 2-3 minutes, which to me sounds like more of a well problem than the pump. The pump can only pump the water at the end of it's suction line. Once that's gone it needs time to recover. I hate to say it, but it may be time to put a deeper well in. The water table may have dropped to a point where you don't have much of a reservoir, or not what there was a few years ago when the well was originally installed.
You need to call Mr. Well guy and have him look at it. All I can do is guess from here. But I think the pump is not the problem. Although, if you are lucky, it could  a pressure  a pressure switch adjustment, or bad  switch.                Let    me know if there is any news.                           Jim