so i am checking the fuel system on my j-spec swap, and it juts flows continuously when i jumper the fuel pump...i read in the hayes manual it should fill, and then stop...but if it keeps going then i need to fix something.


Could it be my FPR? I have another i could swap in....

any good ideas?

-Matt

 

No, if the Haynes says that then they are wrong as rain.

The pressure in the rail will be around 37psi with the jumper plug jumpered and engine off.

The fuel pump puts out around 90 psi. So, anything over the 37psi gets sent back where it came from. Thay's why if someone premixes he does not worry about the premix getting mixed with the fuel..........continuous flow from the tank to engine and back. Always a flowin

 

That's exactly what's supposed to happen. That's what the check connector is for.

Either the Haynes manual is wrong or you've misunderstood it. On S4's the fuel pump is not controlled by the ECU and will only run if the AFM registers airflow or the key is in the start position or the check connector is jumpered. On S5's the fuel pump is ECU-controlled so it might run the pump for a few seconds to prime the system, but this has nothing to do with the check connector and would be pretty pointless anyway.

The FPR has nothing at all to do with running the fuel pump.

 

OK, well i hooked everything back up and its running smooth as butter...nice idle with NO lope at all...now im kinda glad my old engine blew...