have someone go back there while you are driving or vice versa, and keep an eye on it, make sure its dry when you put it in the water and check where the first leak springs. In my boat I get water in through the front of the pump at higher rpm's and about a drip every 10 seconds from where the steering cable comes in through the transome adapter. In a jet there are a few places it can leak from, jets typically leak it seems like, the seal where the pump intake meets the hull, the transom adapter, the steering and reverse holes, the front of the pump or the hand hole if its inside the boat. Other than that you could have a hole or a crack in the bottom, I had 2 little holes from where someone drilled the bilge pump to the transom, I JB welded them up and no more leaks. For now put an automatic pump and let the good times roll !!