Hello! I have a sprinkler system that was installed when I built our home in 1988. All worked well until recently. I have a 4" well that is 54' deep, the static water depth is approx. 8', the dynamic water depth is appox. 10'. There is 25' of 1 1/4" sch40 down with a foot valve all of this is hooked to a 2hp electric external pump. The footvalve, pump and pressure switch were purchased and installed on 4/8/07. The former pump was 1.5 electric, approx. 3 years old when the pressure starting fluctuating from 35 psi down to 5psi with an equal drop in water output to the sprinkler system plus the system would not shut off. The system is hooked to a pressure tank that is approx. 2 years old. I called a local well company and they came out looked at the setup said it was the pump and wanted to sell me a $900 pump. I said no thank you and went to a retail chain and purchased the above mentioned pump for less than $300. The pump, pressure switch and foot valve were istalled with no change, that is, pressure and water output are still fluctating and system will not shut off. I have a cut off to the sprinkler system and a hose bib that I can use seperatly. I have run the pressure up to 40psi, shut all open valves but pressure switch does not cut system off, however, system will stay pressuized overnight to approx 40psi when I manually shut off at the breaker. I do not see any water leaks from pump to tank. All suggestions will be greatly appreciated.