I have a 100' well with submersible pump, approx 15 years old. The other night I heard it running for an extended period and found it was about 5 psi under cutout (60) but not increasing. After turning the pump off and waiting several hours this condition remained. Due to neccesity I lowered the cut-out setting to 45 so that I could get it to operate automatically. This appeared to work then. However, this evening I found again the pump could not achieve this new cut-out setting and was running continuously, so I was forced to lower it yet again, to about 40psi. This is a 1/2 hp Sta-Rite pump, 240 volt, again 15 years old. I checked current draw of the unit, I found settled current draw of 5 Amps. I also shut off pump and house side main water valve for several hours and was able to maintain constant pressure. This system also uses what appears to be a 40 gallon bladder tank, but this appears to still be in good condition. I adjusted the tank pressure to be just under cut-in of pump control both times.

So my question is, do you suspect worn out pump ?
Or a cracked riser line? Or maybe a failing check valve?
Or maybe some other scenario that I haven't thought of ?

Your help is appreciated
Thanks,
Morrowrj

If your tank is empty when you check it, and you pump is still running ,check your float
Ball. This is a common problem and will eventually blow the pump. You can check it by raising the float manually and checking it to see of it shuts on and off. Shake it. If this is the problem it should fix itself by shaking or tapping it. Good luck

It does sound like the pump. I'm not sure what ME is talking about involving a float valve. I would think you are adjusting the pressure at the switch. I would, just to be sure, check the tank to be sure the bladder is still holding. You can do this by pressing the air valve at the top for a couple of seconds. Should only be air coming out, not water. You can also tap up the side with a screwdriver handle. The "tone" will change when you hit air, hopefully about halfway up. Still, when it won't pump up to cut out pressure, that sounds like the pump. If it was the checkvalve, you would notice a rapid drop in pressure when the pump cuts off as water drained back down the well pipe into the well.

Well, I don't know what MEShell is talking about, this is a drinking water well, not a drain sump. Anyway, the tank checked out OK. I ended up pulling the pump and replacing. The pump continued to loose the ability to reach max pressure over the following 24hrs after my first post. Thanks for your help

Morrowrj