presoak losing prime

[Reds]

I have a Cat 3k133 end suction centrifugal presoak pump. Yesterday it lost it's prime for the second time in 2 weeks. I had the wash shut down for the better part of the day and when I fired it back up I had no presoak pressure or delivery. But I could hear the pump running. When I loosened the bleeder bolt at the top of the pump housing all I got was foam out of it. So I ran the pump manually until I got a good stream of presoak out of the pump, tightened the bolt, and it has worked fine since. The pump is gravity fed (JC equipment) from a tank above, then pumps out the top of the pump, thru a check valve, and directly out to the gantry. The only thing in between the tank and the pump is a strainer inside the tank, which is clean. Any idea what would cause it to lose it's prime? I have had the bay shut down for a day in the past with no trouble. The tank was full of mixed presoak when this happened.

Thanks in advance for any input.

 

[Buzzie8]

I had problems with my JC presoak but with a procon pump. If I remember correctly I was getting an air lock in the hose from the tank to the inlet on the pump. My distributor said to always take the outlet hose off and prime pump before running. If procons run dry their toast!