Fuel Pressure Control Solenoid: Description and Operation

Fuel Pressure-Up System Circuit Schematic:

The Fuel Pressure-up Vacuum Switching Valve (VSV), located on the RH side of the engine, controls the vacuum to the Fuel Pressure Regulator (FPR). When the ECU senses high coolant temperature, it grounds the VSV via terminal FPU and interrupts manifold vacuum to the FPR. This initiates a 6 - 7 psi increase in fuel pressure at the injectors. The lean fuel condition, caused by high engine temperature, is enriched by the increased fuel pressure.