Midget Farmer, From your description it seems like someone has bypassed the double fuel pump. The line that goes to the block does nothing, the line from the intake manifold going into the cab is the bypass of the double pump. The routing of the lines is easy, disconnect them both from the pump, start the engine and put your finger on the openings. The one that sucks your finger in is the one to connect to the manifold, the other one goes to the wiper motor. I would guess the pump was bypassed because it isn't working, if so you will need to replace the diaphragm on the upper part of the pump to achieve the vacuum boost desired.
