Fuel Pressure Regulator Control System

PURPOSE
The fuel "pressure up" control system briefly increases fuel pressure for improved starting performance of a hot engine.

Fuel Pressure Regulator Control Input And Output Chart:

OPERATION
Under normal operating conditions, manifold vacuum is applied to the fuel pressure regulator.

Vacuum Solenoid:

Fuel Pressure Regulator Control:

The vacuum supply hose has a control solenoid intersecting it. During hot engine start, with fuel temperature above 75°C (167°F), the Engine Control Module (ECM) energizes the ON/OFF solenoid connected to the manifold vacuum supply hose. The energized valve vents to the atmosphere. As a result, atmospheric pressure is applied to the fuel pressure regulator to increase fuel pressure.