Fuel Pressure-Up System
- Ensure coolant temperature sensor, air temperature sensor (in airflow meter) and circuits are operating correctly. See ENGINE SENSORS & SWITCHES .
- Ensure coolant temperature switch is operating correctly. Switch is in side of engine block and has a Pink wire attached. There should be no continuity between switch terminal and body when coolant temperature is less than 208°F (98°C). There should be continuity between switch terminal and body when coolant temperature is more than 220°F (105°C).NOTE: The ECU uses signal from coolant temperature sensor to control ground circuit for fuel pressure-up vacuum switching valve.
- Fuel pressure-up system is controlled by ECU through a vacuum switching valve. The vacuum switching valve is fed current through the EFI main relay when the ignition is turned on. ECU controls the ground circuit. ECU will activate vacuum switching valve for 90-180 seconds when restarting engine at normal operating temperature.
- Remove VSV from vehicle. See Figure. Check for continuity across valve wiring terminals. Resistance should be about 33-50 ohms at room temperature. There should be no continuity between each terminal and body of valve. To check operation, see Fig 1.