We replaced a shallow well pump however there are problems. The pump comes on erratically and takes forever to come on when we use the water. We don't know what the pressure reading should be and we have adjusted the pressure switch a lot. What should we do?

The switch is supposed to come on at some point, for example 30#, and then turn off at about 20# above that point. There are two nuts on the pump to adjust this. The larger one will adjust BOTH pressure points up or down, while the smaller one adjusts only the cut off point up or down. Turn clockwise to turn up, or ccw to turn down.

How long it takes for the pump to kick in is not the point. It should simply come on at the same point every time, and turn off at the same point every time. Does it do that?

Not sure what you mean by "comes on erratically".

This site will tell you a lot about adjusting the switch.

How to adjust water pump pressure, pump cut-on pressure and pump cut-off pressure - private pump and well system do-it-yourself repairs (http://inspectapedia.com/water/WaterPumpAdjust.htm)

Hi. It does shut off at the same time and come on at the same time. Well it has been until we have fiddled with the larger bolt. The pump comes on when it shouldn't, about every ten minutes. There is hardly any pressure now. I think I may go and get a new pump tomorrow.
Thanks for your info!

Hold on, pardner! The pump does not control when it comes on, the switch does that. The main thing you need to check is this: When the pressure is too low, then pull the grey cover off the switch and see if the sets of points are touching. If they are touching, then the pump should be on. If they are touching and the pump is still not running, then maybe you have a pump problem. And if you have a pump problem, then it should be under warranty.

Did you have this problem with the old pump, or did it just appear with the new one? Who installed the new one? If it was a pro, then you need to get them out there to check out the problem.

Did you replace the old switch when you put on the new pump? If not, then it is possible the contact points on the old switch are your problem.

One last thing. If the pump is coming on "when it shouldn't", then it is possible you have a leak somewhere. That pressure gauge is your best friend in trying to assess the problem. When the pump cuts off, does pressure hold, or does it slowly drop?

A lot of questions I know, but trying to keep you from spending money needlessly on a new pump.