Fuel Pressure Control Solenoid: Description and Operation

Fuel Pressure Solenoid Circuit:

Description
The fuel pressure control solenoid valve is an electromechanical, vacuum switching valve.

Purpose
The ECU uses the fuel pressure control solenoid to control the vacuum to the fuel pressure control valve--raising fuel pressure from approximately 26 psi to approximately 36 psi during hot restart conditions--reducing the chance of fuel boiling in the fuel rail.

Location
The purge control valve is mounted to a bracket on the LH firewall.

Operation
When the ignition is turned on, the control relay applies 12 Volts to the solenoid.

During cranking if the coolant temperature sensor indicates 194° F or higher and the air temperature sensor indicates 122° F or higher, the ECU will ground the solenoid.

As a result this will bleed off the vacuum and raise the fuel pressure to 36 PSI. The ECU will keep the solenoid grounded for 2 minutes and increase the injector pulse width to help purge any fuel vapors in the injectors.