this is not a FI question it is a electronics question. So you did clarify the question to a point.

 

On this, I can clarify. No signal is sent to change the way the fuel pump operates. It is pumping at more or less the same pressure all the time. It is the FMU that changes the pressure in the fuel rail and the FMU is controlled by vacuum (or boost) as sensed directly from the intake manifold. The stock regulator becomes defunct when boost is detected. It's like putting a bigger dam downstream of the smaller dam (stock reg.).

 

xviper,

Why was the fuel pump upgraded if there is no signal telling it up the PSI inorder to deliver more fuel?

 

It delivers more fuel all the time. The FMU is what controls the pressure by allowing unneeded fuel to flow back to the tank.

 

[QUOTE]Originally posted by gernby
[B]It delivers more fuel all the time.

 

I know Jack Schitt. He and I go way back.

 

jack and I know each other really well also. That is why I am asking these questions.