High Temperature Pressure Up Fuel Pressure Control

Some engines are equipped with a high temperature fuel pressure control to prevent vapor lock for easier starting and better driveability. A three way VSV is connected to the fuel pressure regulator vacuum line. Under normal conditions, the VSV is off and engine vacuum regulates the pressure regulator. If the engine is started when the coolant temperature is 85'C (185'F) or higher and the intake air temperature is above predetermined level, the ECM will turn on the VSV. Engine vacuum is closed off and atmospheric pressure is applied to the pressure regulator diaphragm. This increases fuel pressure preventing vapor lock. Once the engine is started, the VSV may remain on for about 120 seconds.

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