Its winter and I'm having issues keeping water pressure in my system. Sometimes I can get it but as soon as the pump kicks on the pressure fluctuates dramatically and then goes to 0 and stays there. I then close the valve between the pump and pressure tank so I can prime the pump. When I check the lines they are full of water including the pump itself. So I have prime right? If the pump is running and isolated from the pressure tank it normally will built pressure fast then shut off, loose pressure and come back on doing this continues. I think this is normal because its not going to the pressure tank. When I open the valve to the tank rather than building pressure slowly it will fluctuate and 9 times out of 10 it will go to 0 after a while. However at this moment it built pressure.

So my question is, If the foot valve is bad would it build pressure at all? Or would it sometimes build and sometimes not? Can a pump act this way? Any way to test the pump?

It's a deep well with a jet pump. 2 lines going into the well. There is a lot of iron in our water and there is an orange film in the lines. I have a T in each line at the pump with a plug so I can prime easily. I did this because it happens a lot in the summer and filling at the top of the tank is a pain. When I pull the plugs out I can see the water is right to the top, same with the pump. Frustrating as hell.

I'm going to experiment tonight. The system is pressurized at the moment. I will close the valve between the pump and pressure tank for the night and see if it looses pressure. I see no movement in the pressure gauge of a short time but perhaps over night it will drop. This should indicate if I have a leak or a bad foot valve right? I'm about 1 day away from buing a new pump just to rule it out.

Help please. Mike