have you tried using an auxiliary fuel source and putting it higher than the injection pump so that it gravity feeds into the pump? and when you do that check to make sure fuel comes out of the return line when you are pumping the manual primer pump. another thing is take off the injector hard lines and crank the engine over by hand and make sure the pump is squirting nicely at the injection pump.. it should be a huge squirt that hits the hood... so make sure to be out of the way..