Bigle pump keeps backflowing

[lnewport]

My r39 and a rulemate 1100 bilge pump. I think whata happening is that it moves water out of the bilge but some water remains in the pipe. It drains through the joker back into the pump which it fills the small bilge and it gets pumped back in to the pipe and repeat every 30 seconds forever.

I have changed the joker valve, that didnt help, maybe as the pipe is horizontal, there is no pressure to close the joker?

[vasko]

Was same here, remove the original rule non-return valve and put a proper jabsco one - and all will be fine