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  • Returnless Fuel System - Operation

    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...

    Originally posted by Rara View Post
    It could be done, but it would require swapping in/out a number of other components to allow the fuel delivery to be controlled properly. Not something you could do in a weekend unless you had worked it all out and had all the correct parts on hand.
    so... what components would be needed?

    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...
    -Mike
    If you are wondering where the avatar came from look here... Link
    98 SVT Contour - HoK TruBlue|CF roof|#49/6535 DOB 3/25/97|550whp here I come|Follow my extremely slow 3L/turbo build here Link
    85 Camaro - 1969 350ci, 503BHP

    Owner - RIES PEFORMANCE

  • #2
    I have always thought return was more ideal for higher hp applications.
    '98 SVT E0 BLK/MNB#1663 3L Always broke.
    '99 SVT E1 BLK/TAN#0741 Sold
    '07 MAZDASPEED3 GT

    Comment


    • #3
      Originally posted by Beans View Post
      I have always thought return was more ideal for higher hp applications.
      Only benefit that I could see from return vs returnless is the possibility that the fuel temperature could be cooler with that of a return style. Other then that... everything else would be the same I would think.
      -Mike
      If you are wondering where the avatar came from look here... Link
      98 SVT Contour - HoK TruBlue|CF roof|#49/6535 DOB 3/25/97|550whp here I come|Follow my extremely slow 3L/turbo build here Link
      85 Camaro - 1969 350ci, 503BHP

      Owner - RIES PEFORMANCE

      Comment


      • #4
        I'm sure someone will chime in, but i know for a fact that some Terminators owners convert to return, i believe SRT-4 owners too...
        '98 SVT E0 BLK/MNB#1663 3L Always broke.
        '99 SVT E1 BLK/TAN#0741 Sold
        '07 MAZDASPEED3 GT

        Comment


        • #5
          The difficulty here is that I need to use the returnless fuel rail regardless of whether it functions with the current system as a return style or if I convert the existing system to returnless. So if the benefits of a return style are in fact just cooler running fuel temps then I won't be completely capitalizing on that because the fuel rail I have to use is not built to operate that way and the fuel will not be flowing through it the same way it would with a return style fuel rail. I guess we'll see what someone with more experience chimes in with. Otherwise I'll bounce this question off some of the engineers on the engine team at work next week when I get back on the 5th.
          -Mike
          If you are wondering where the avatar came from look here... Link
          98 SVT Contour - HoK TruBlue|CF roof|#49/6535 DOB 3/25/97|550whp here I come|Follow my extremely slow 3L/turbo build here Link
          85 Camaro - 1969 350ci, 503BHP

          Owner - RIES PEFORMANCE

          Comment


          • #6
            why not just use the NPG fuel rail mod? it was designed to allow the use of the returnless fuel rail on return system cars.
            TZT Performance http://www.tztperformance.com/
            officially a troll. '93 3000GT VR4 #2229/2595

            '00 Black SVTC - sold 5/1/10
            '97 GL Turbo Zetec - gone

            Comment


            • #7
              I know you'd like to use that rail and you still might be able to, but for your plans and power level I would only do return style.
              -J
              '99 SVT Silver
              Clean DD
              '91 LX Bimini Blue
              427"/88mm @ 16psi....yeah 4 digit power

              Comment


              • #8
                Originally posted by biminiLX View Post
                I know you'd like to use that rail and you still might be able to, but for your plans and power level I would only do return style.
                -J
                What's your opinion as to why the return system should be used?
                -Mike
                If you are wondering where the avatar came from look here... Link
                98 SVT Contour - HoK TruBlue|CF roof|#49/6535 DOB 3/25/97|550whp here I come|Follow my extremely slow 3L/turbo build here Link
                85 Camaro - 1969 350ci, 503BHP

                Owner - RIES PEFORMANCE

                Comment


                • #9
                  Originally posted by CSVT#49 View Post
                  What's your opinion as to why the return system should be used?
                  Safer for big power IMO, thats why you rarely see the big HP cars run returnless, they are almost 100% return.
                  I like a mechanical regulator and more supply over electronic sensors calculating how much fuel I need when I drop the hammer. More reliablity with a return also, but I never had a problem with the FPRS in my '04 Cobra but lots of my friends did.
                  -J
                  '99 SVT Silver
                  Clean DD
                  '91 LX Bimini Blue
                  427"/88mm @ 16psi....yeah 4 digit power

                  Comment


                  • #10
                    Most I have seen work like this.

                    http://autospeed.com/cms/title_Modif...7/article.html
                    This one has a little at the bottom about returnless.
                    http://autospeed.com/cms/A_2636/article.html

                    If I were you I would use the old feed as the return line and buy some -6an ss braided and use that to make the new feed. Its not going to be plug and play though.
                    B5 Audi A4: GT3582R - Custom Stainless Manifold - Megasquirt II V3.0- Custom 3" Downpipe/Exhaust - Daily Driver
                    95 SeVT: Custom GT42 Turbo - Dual Scroll Custom Stainless Y-pipe - Dual Open 44mm WG's - 4" Downpipe - 3" exhaust - Autronic ECU

                    Comment


                    • #11
                      Originally posted by 2000ZxT View Post
                      Most I have seen work like this.

                      http://autospeed.com/cms/title_Modif...7/article.html
                      This one has a little at the bottom about returnless.
                      http://autospeed.com/cms/A_2636/article.html

                      If I were you I would use the old feed as the return line and buy some -6an ss braided and use that to make the new feed. Its not going to be plug and play though.
                      Good idea, you want enough fuel to be safe with a built 3L turbo.
                      -J
                      '99 SVT Silver
                      Clean DD
                      '91 LX Bimini Blue
                      427"/88mm @ 16psi....yeah 4 digit power

                      Comment


                      • #12
                        Yes the more I think about this I am going to have to revamp the fuel delivery system a little more beyond just upgrading the fuel pump to the 255LPH version.

                        When I finish removing the engine, trans, and exhaust I'll siphon the tank and replace all of the lines and connections to allow it to support the monster I am creating.

                        Ugh... my April 30th deadline is coming up sooner then I would like with all of the little details I have not been planning for...
                        -Mike
                        If you are wondering where the avatar came from look here... Link
                        98 SVT Contour - HoK TruBlue|CF roof|#49/6535 DOB 3/25/97|550whp here I come|Follow my extremely slow 3L/turbo build here Link
                        85 Camaro - 1969 350ci, 503BHP

                        Owner - RIES PEFORMANCE

                        Comment


                        • #13
                          Glad thats cleared up. Don't worry about a deadline, at least you will have it done right and how you want it.

                          While we are on this topic i was curious, is the stock fuel pressure regulator sufficient enough for a 255lph pump?
                          '98 SVT E0 BLK/MNB#1663 3L Always broke.
                          '99 SVT E1 BLK/TAN#0741 Sold
                          '07 MAZDASPEED3 GT

                          Comment


                          • #14
                            I am not sure where you are going with this project but I ran over 500hp and I had more than enough fuel using the stock fuel lines.
                            www.nautilusperformance.com

                            99 SVT #198 blk/blue
                            Spec 3/quaife/stage 2 shafts
                            T3/T4 60-1 fully built 3.0 liter
                            oval ported heads
                            400whp 410wtq 13 psi
                            13.2 @ 107 mph
                            clifford alarm and turbo timer
                            koni struts H&R springs

                            Comment


                            • #15
                              Originally posted by BurritaSVT View Post
                              I am not sure where you are going with this project but I ran over 500hp and I had more than enough fuel using the stock fuel lines.
                              I never knew you ran more then 500hp at the wheels? So Joey what did you run for a fuel pressure regulator, fuel rail, and fuel pump?
                              -Mike
                              If you are wondering where the avatar came from look here... Link
                              98 SVT Contour - HoK TruBlue|CF roof|#49/6535 DOB 3/25/97|550whp here I come|Follow my extremely slow 3L/turbo build here Link
                              85 Camaro - 1969 350ci, 503BHP

                              Owner - RIES PEFORMANCE

                              Comment

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