Description and Diagnostic Procedure

SYSTEM: Vacuum Switching Valve for Fuel Pressure Control





CIRCUIT DESCRIPTION
The engine control module turns on a vacuum switching valve 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 100 secsonds after the engine is started.





DIAGNOSTIC PROCEDURE

1. Check operation of Vacuum Switching Valve for Fuel Pressure Control
- If OK proceed to step 2.
- If not OK replace Vacuum Switching Valve.
2. Check voltage of Vacuum Switching Valve 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 Engine Control Module.
- If OK check and replace Engine Control Module.
- If not OK repair or replace harness or connector