Image Number 6 for United States Patent #4231390.
A fuel spray bar is disposed in the induction passage of an internal combustion engine for spraying fuel into the induction air stream. The spray bar contains a pair of separate fuel distribution rails designated as the main (or light load) fuel distribution rail and the auxiliary (or power) fuel distribution rail. A plurality of spaced orifices communicate each rail with the induction passage. A pressure regulator assembly is disposed on the fuel spray bar and contains a main pressure relief valve assembly, the outlet of which is in communication with the main fuel distribution rail of the spray bar and an auxiliary pressure relief valve assembly, the outlet of which is in communication with the auxiliary rail. A motor driven control pump delivers fuel to the inlet of the pressure regulator assembly. At idle and light engine loading, only the main valve assembly is open so that fuel is sprayed into the induction air passage solely via the main fuel distribution rail and its orifices. For greater engine loading the auxiliary valve assembly is also open so that fuel is distributed via both rails and their orifices. The structure of the pressure regulator assembly is configured to render incorrect assembly thereof readily apparent.