I'm trying to figure out what all would need to be done to change over a return style fuel system to a returnless system.
So I found an old thread, which somewhat asked the same question I had, but not to the level of detail I had hoped. So I am starting a new one for search purposes...
I'm trying to think through what all happens, is an open loop system?
-ECM turns on fuel pump
-fuel pump pumps fuel through line
-fuel reaches pressure regulator, which regulates incoming fuel to set pressure
-Returnless: ECM monitors fuel pressure regulator creating a closed loop and adjusts fuel pump output??
-ECM turns on injectors accordingly
-injector sprays fuel into cylinder
-Return: excess fuel cycles back to tank??
Reason why I ask is that my 2005 ST220 fuel rail is a returnless rail, but it has no electronic monitoring fuel pressure sensor like my 2005 Escape rail has on it. So I am wondering how the returnless system operates on the ST220 Mondeo. I am assuming it would be an open loop system since there is no feedback to the ECM regarding fuel pressure, which if this is the case then I don't see why a returnless fuel rail couldn't be swapped into a return style car. If this is true then all you would need to do (again making an assumption here) is remove the unused return line and plug the corresponding ports on the tank. This should not have any effect on the fuel pump as it only has an inlet and an outlet. The only thing that could potentially be effected is the output from the ECM to the fuel pump, however if the system is truly open loop and the ECM is not monitoring the fuel pressure regulator then there would be no change in the ECM output to the fuel pump anyway.
So that said... thoughts, comments?
EDIT: I just thought of this... unless the ECM is monitoring fuel pressure at the fuel pump, but this would not make sense as it would need to look at the pressure after the regulator where it matters...