I have a drilled well with a 4 inch casing 96 ft deep. In 2002 I had to put in a new pump. Two weeks ago I ran out of water. We metered the pump and it seemed to be working. Last weekend we decided to raise the pump up a little and fill the casing with water. When we turned the pump on it would pump water directly out the top of the pump, and then would come to a stop. We decided the well was probably dry. This weekend I decided to turn on the pump again to see if it had recovered, and there was no water at all. I then raised the pump again and filled the casing with water and could get it to pump. Still not convinced that the well is dry I droped a line down the well and I could hear the weight hit water. I marked the string at that point, and continued to lower the weight to the bottom of the well. It showed I had 43 ft. of water. Why will the pump only pump water when I fill the casing up to the top?