If it only works out of water then the prop is probably to big for the pump. Does it work if you start the mj out of water and then put it in? Also the depth of the mj in the water wakes a difference. Try starting it higher up. Which prop did you get?
Tried that mod on 2 pumps...one mj knock off that came with nano and a surge 3000 800 gph.... Don't see much of a difference the water just comes out of the drilled holes not that those guys would notice, thats why their sand is blowing all over the place...