FPR help

[apedog]

Im buying a Walbro255 but since I read you need an FPR I guess I need one haha

My question is what should the gauge say when everything is installed.

Thanks

 

[dented_coffee]

Mine was arround 45psi and ran great. Make shure you prime the fuel system first thow.

 

[steve]

1G manual turbo cars run 36.3 psi base fuel pressure (pressure with the vacuum line to the FPR disconnected) and the 1G automatic cars run 42.7 psi. Changing the base fuel pressure will require retuning the car since it effects the flow rate of the injectors.

 

[apedog]

1G manual turbo cars run 36.3 psi base fuel pressure (pressure with the vacuum line to the FPR disconnected) and the 1G automatic cars run 42.7 psi. Changing the base fuel pressure will require retuning the car since it effects the flow rate of the injectors.

i got an auto so im looking for 42.7 psi. Now what should it be at idle or does it go up to that when you start to press the gas?

 

[steve]

i got an auto so im looking for 42.7 psi. Now what should it be at idle or does it go up to that when you start to press the gas?

There are many threads on how the FPR works and it's covered in some detail in the technical manual and service manual. You should read them if you haven't yet.
You'll find links in the FAQ section.

The simple answer is the vacuum line when connected changes the fuel pressure 1:1 with manifold pressure (positive or negative) so that at idle the fuel pressure drops and under boost the fuel pressure rises but the difference between the pressure difference between the inlet of the injector and the outlet of the injector is always equal to the base fuel pressure. This way the ECU can get the same amount of fuel per unit time from the injectors regardless to the throttle position and engine load.