Question
Hello-  I have a small (1.5hp) irrigation pump that just started to cycle on and off really quickly.  Like less then 4 seconds on and off.  I have a 6 gallon pressure tank and pressure switch that has been in use for about 5 years on a shallow Florida well.  Primarily used for hose watering of garden and plants.  The pressure is still good so I guess the pump is fine.

Thanks.

Answer
I would suspect a problem with the pressure tank.  If you have the type that has an air bladder inside, the bladder may be ruptured.  These cannot be repaired (usually) and the tank will have to be replaced.  If you have the type of tank that has no air bladder, it is probably waterlogged, and needs to be drained.  To do this you need to turn off the pump, close the valve or valves between the pump and the tank, and find a way to get all the water out of the tank.  You will usually have to vent the tank to drain it.