After doing some more research, that VSV valve is used in junction with the fuel pressure regulator and nothing to do with the fuel pump relay which controls the voltage to the pump.
When this VSV valve is given a voltage, the vacuum is blead out and therefore causes the fuel pressure regulator to run on max high pressure. I think the ECU activates this VSV when the engine is hot. It works with the THA in the AFM and the Water Temp sensor.
Still doesn't clarify what triggers the FP output for the fuel pump relay, arrg!
Wed, 08 December 2004 21:44
