Fuel Pressure Regulator: Description and Operation

Throttle Body Assembly:

The fuel pressure regulator is used to maintain fuel supply pressure at 14.5 psi with the engine running and upon engine or fuel pump shutdown. The regulator functions as a downstream check valve and traps the fuel between itself and the fuel pump. Maintaining fuel pressure upon engine shutdown precludes fuel line vapor formation and allows for rapid restarts and for stable idle operation immediately thereafter.
The pressure regulator is an integral part of the fuel charging main body and is located near the rear of the air horn.