Need help diagnosing water pump

Old 11-24-15, 01:26 PM
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Need help diagnosing water pump

I am having issues with a water pump and I could use some help diagnosing what could be wrong with it. About a week ago the water stopped running to my home. I checked the pump outside and it was constantly running. The pressure gauge showed 30psi. I figured it might be due to a burst pipe underground but there was no signs of any wet spots in my yard. I cut the output pipe near the pump and I was getting plenty of water. After cutting the pipe I plugged it with my thumb to see if the pump would shut off and it did not.

I was told that the problem was probably caused by a damaged impeller that is not creating enough pressure to cut off the pump. I disassembled the pump and there is no clear damage to the impeller. Can anyone help me understand what is wrong?

1. No water to the house.
2. No evidence of a busted line.
3. Decent water at the pump.
4. The pump will not shut off when the line is blocked.

I'm stumped. Any help would be appreciated.

P.S. The stickers are faded and illegible on the pump so I cannot identify a brand name or model number but I will include a photo.

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Old 11-24-15, 02:05 PM
Join Date: May 2015
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When you blocked the outlet did the pressure rise above 30 psi? I'm guessing not.

It sure sounds like the pump just can't generate enough pressure. Have you looked at the inlet side? If there is a leak in the inlet line, the pump may be sucking enough air to cause cavitation and prevent it from developing enough head to push water to the house and to shut off.

If you have a way to temporarily supply water (hose from neighbor?) to the inlet and it works, then you have a problem on the inlet side.

What is the water source? A shallow well? Is it possible the foot valve is partially above the water level?
Old 11-24-15, 03:35 PM
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Thanks for the response. It never went above 30psi. I haven't checked the inlet side either. I will go take a look at it tomorrow. It's doubtful that I can get a hose back there either.

I'm guessing it's a shallow well. The well was already drilled when we got the property so I am not aware of the depth. I would guess no on the foot valve also. Although I'm not to knowledgeable about wells, I live in Louisiana and our ground is thoroughly saturated with water so I'm guessing that's not the case.
Old 11-24-15, 04:25 PM
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I think it's a Fairbanks-Morse Pump (Made in Italy; based on the color and shape of the pressure chamber only.

I have one and it currently works fine; but having tried, I've never been able to secure an Owner's Manual.
Old 11-25-15, 06:57 AM
Join Date: Dec 2006
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When you manually turn off the pump does the pressure stabilize or does it slowly drop?

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