Lets hope that fixes your issue. Ensure the pump outer part goes on the right way, you will notice there is an arrow, this shold face the rotation of the shaft as the engine spins it. So from memory, looking at the pump from the bucket, the arrow should point to the left. If it's backwards, you will not get flow.
Please check that i have the rotation correct, the engine should turn clockwise, so the shaft at the pump looking from the bucket should be ani-clockwise.
Good luck, the people at LPS are good to work with.