if these units have the cam driven fuel pumps, you can replace them with the pulse style fuel pumps. I've done 4 of them under warranty. this will move the fuel pump up to the valve cover as seen on the newer engines. you need to drill a hole in the manifold to get the vacuum. all the units i have done all had the same symtoms. if unit was ran out of fuel it would not restart. i have not had any issues with the new pumps we put on.