For my fuel injection system I need a high pressure fuel pump (43 psi) which is electric. Also required is a fuel pressure regulator to maintain a constant pressure in the system. Most or all fuel injected engines use a diaphragm type regulator with fuel pressure from the pump on one side of the diaphragm and a spring on the other. When the fuel pressure overcomes the spring pressure a valve is lifted off its seat and excess fuel is allowed to return to the tank. The spring tension determines the fuel pressure. The fuel enters the regulator through one of the A/N type fittings on the side and exits to the fuel injectors on the other. The excess fuel is returned to the tank via the hose barb on the bottom. Since I do not need the old mechanical fuel pump I decided to cut the top off of it and mount the regulator in its place. This kills 2 birds with one stone. A mount for the regulator and a block off plate for the hole in the block. Plus I am trying to keep the truck looking like a vintage 60's style hot rod and at first glance the regulator looks like the stock fuel pump. I hope that answerers your question.
