On my fuel pump there are three fittings. One is the inlet for the fuel, the other one is the outlet. What is the other one on the side for. I would think that is for the air to pump the fuel. I am just trying to clarify. Thanks.
The 3rd line is the pulse hose connected to the crankcase. The pistons going up and down create the pulses, kinda like suck and blow to move the diaphragm.