i have what looks to be a double drop jet pump system. it has a 1/2 hp gould pump on it.. when i bought the house last summer it didn't have enough pressure to make a sprinkler turn. just sprays straight out. this summer i have replace the pressure tank that wouldn't hold pressure and the pressure switch. the pump would constantly run. it is a 20 gal bladder style tank ( same as the original). the pressure switch is 30/50 psi. i have the pressure tank at 28 psi. i made the change in hopes to increase my pressure and flow. when i turn on the system. the pump still runs constantly and the tank still won't fill. how do i get the tank to fill? and will this help increase my pressure? if not what would be the fix. when of the pressure gauge reads at 28 psi and increases around 10 to 12 psi when the power is turned on. just using is for the yard. 2 fixtures.