Description and Diagnostic Procedure

SYSTEM: Vacuum Switching Valve Fuel Pressure Control Circuit

CIRCUIT DESCRIPTION



The ECM turns on a vacuum switching valve (VSV) to draw the air into the diaphragm chamber of the pressure regulator if it detects that the temperature of the engine coolant is too high during engine starting.
The air drawn into the chamber increases the fuel pressure to prevent fuel vapor lock at high engine temperature in order to help the engine start when it is warm.
Fuel pressure control ends approximately 120 seconds after the engine is started.

DIAGNOSTIC PROCEDURE

VSV For Fuel Pressure Control Circuit:

1. CHECK OPERATION OF THE VSV FOR FUEL PRESSURE CONTROL.
^ If OK proceed to step 2.
^ If not OK replace the VSV.
2. CHECK VOLTAGE OF VSV POWER SOURCE.
^ If OK proceed to "Diagnosis By Symptom".
^ If not OK proceed to step 3.
3. CHECK FOR OPEN AND SHORT IN HARNESS AND CONNECTOR BETWEEN MAIN RELAY AND ECM.
^ If OK check and replace ECM.
^ If not OK repair or replace harness or connector.