Fuel pressure regulator
The fuel pressure regulator is a bypass style that references the manifold pressure. As the boost goes up, the fuel pressure is increased, keeping the fuel pressure a set amount above manifold pressure. Without a regulator that referenced boost, for example, if the fuel pressure were 25 lbs and the manifold pressure were 25lbs, no fuel would flow! This regulator is set for 50lbs of fuel pressure with no boost.