try again...lost prime

I have a 90' drilled well with a 2 line jet pump. My pump was cutting in and out every couple of minutes. I watched and it would cut out at 52 PSI...I thought that was good. After it would cut out, I watched the pressure gauge and the needle would immediately quiver downward and the pump would cut in at 40 some PSI. I did not know why there was a sudden drop in pressure, but I thought the pump was turning on pre-maturely and assumed a bad pressure switch. My water worked fine in the house at this point.. ...I turned off the power to the pump. There is a tire valve stem (similar to the one on the pressure tank that is mounted next to the ouput line on the pump. I pulled off the rubber boot on this and it started dripping. I depressed the needle valve temporarily to try to get it to seat. It let out a small amount of water/air so I capped it with a tire valve stem cap to temporarily stop any leakage. I then turned the power back to the pump. It came on as expected. However, it stayed on and would not build pressure. Stayed at 40 some PSI. I check my house water and had none. I assumed I lost my prime. I disconnected the pump outlet line that feeds the pressure tank and gravity fed water to fill the pump casing and top off the inlet lines. (only other way to prime was into plug, but that was side mounted and did not work well) I thought a gallon would do it, but ended up pouring 15+ gallons in before it started to appear full. I tried to run the pump and expected the prime to take and have water pumping everywhere. It did nothing. In fact it would then take more water. Do I have a bad foot valve? or leak in inlet line? Help!

If I understand you, you opened the air valve on your bladder tank and it let water out? If so, then your bladder tank is shot. Things won't be right until it is replaced.

Thanks jadnashua - It was not the pressure tank (air bladder) stem. The pressure tank was holding air pressure and did not appear waterlogged. The tire stem that I was referring to (which I have now replaced) is on the pump. There is a "junction fitting" that extends out the end of the pump. It has 3 ports. One on top and one out each side. The one out the top is where the pump output line is threaded into (this feeds the pressure tank). One of the 2 sides has a square "access plug". The other side is the "tire valve stem" that I was referring to (that leaked a small amount of air/water). I was told that this small amount of discharge probably did not cause my loss of prime, but rather the pump was cycling rapidly because it was fighting to keep the water in the input line due to a leak or faulty foot valve. When I shut it off, it drained back and lost prime?? This theory seems to make sense to me?? Any comments out there??

I think your theory is very plausible. A bad footvalve (or a leak in a suction line) would certainly cause the problem you are having. On a twin pipesystem, the footvalve is below the ejector down in the well.
Ron

Thanks for the input Pumpman....I will know more tomorrow.