This may sound stupid, it did to me until it worked. I have a 2011 Triton 19XS and both aerator pumps had a very hard time priming. I called Triton boats and they told me to make sure the hose that feeds the livewells is facing to one side of the boat or the other, basically parallel to the bottom of the hull. I checked the location of mine and the hoses were facing slightly downward, I adjusted the pumps to make the hoses run straight out the side and they work properly now. Like others have said check for any air leaks and that the pumps are under water. If none of this works try another pump.