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Replacing M42 Fuel Pressure Regulator

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    Replacing M42 Fuel Pressure Regulator

    Hi all, in an effort to chase down a "warm restart crank but no start" bug on my '91 318is, I have parts on the way to replace the Fuel Pressure Regulator (P/N: 0280160567).

    Would I be able to replace the FPR without removing the entire upper intake manifold + fuel rail?

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    I see that the FPR is secured with a circular clamp with one screw on it, but not sure if I'd be able to get enough leverage to remove the FPR without taking out the entire fuel rail.

    #2
    The FPR is a simple device and easy to check. If there's fuel coming out of the vacuum line, it's done. If it hold vacuum, it's good.

    That aside, you should be able to get in there, but honestly the m42 manifold takes only minutes to remove so you have access to the rail. The hardest part is going to be getting the old one out in that position, they tend to stick quite well at this age.
    john@m20guru.com
    Links:
    Transaction feedback: Here, here and here. Thanks :D

    Comment


      #3
      No, the FPR is going to be hard to remove as the o ring that seals it to the rail is likely going to stick. Additionally, the clamps fastener may be completely inaccessible. You should do all eight injector o rings too as you will at least be removing them from the lower manifold.

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        #4
        ForcedFirebird Thanks for the tip, I'll check on that vacuum line. I'm also replacing crankshaft position sensor, fuel relays, O2 sensor while I'm at it based on reading other posts here.

        I'll attempt the direct FPR removal, and if that fails look into rest of manifold disassembly!

        Comment


          #5
          Recently replaced the fuel injectors (Bosch P/N 0280156372) and 2X fuel supply hoses coming into the fuel rail:

          Click image for larger version

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          Although it seems to have improved throttle response and idle, still got caught this weekend in the warm restart no start trap.

          Comment


            #6
            The new injectors look short.
            Last edited by fresh_TD; 07-06-2020, 04:06 PM.
            '91 318i (Alpine) - daily
            '88 325ix (Zinno) - drive here and there!

            Comment


              #7
              They aren't too short, note the spacing between the o-rings. They are just the newer style EV1.
              john@m20guru.com
              Links:
              Transaction feedback: Here, here and here. Thanks :D

              Comment


                #8
                Originally posted by ForcedFirebird View Post
                The FPR is a simple device and easy to check. If there's fuel coming out of the vacuum line, it's done. If it hold vacuum, it's good.
                If it takes a few seconds to start the engine, does it mean that the fuel pressure regulator or the fuel pump allow the fuel in the fuel hose to spill back into the tank?


                Comment


                  #9
                  Originally posted by Vincenze View Post
                  If it takes a few seconds to start the engine, does it mean that the fuel pressure regulator or the fuel pump allow the fuel in the fuel hose to spill back into the tank?

                  Long cranking times often mean that the fuel pump check valve is nonfunctional or sealing poorly. An in line check valve as close as possible to the pump outlet solves this effectively.

                  Comment


                    #10
                    Originally posted by roguetoaster View Post

                    Long cranking times often mean that the fuel pump check valve is nonfunctional or sealing poorly. An in line check valve as close as possible to the pump outlet solves this effectively.
                    This. Or the veins are worn if it is the fuel system.

                    A fuel pressure tester would make quick work of that diag.

                    A backyard way of kinda checking the pump and check valve is a fuel volume test. Pull the supply line, point into a container, energize the fuel pump and start a timer. You need 1l/qt in about 15sec.
                    john@m20guru.com
                    Links:
                    Transaction feedback: Here, here and here. Thanks :D

                    Comment


                      #11
                      Originally posted by ForcedFirebird View Post

                      This. Or the veins are worn if it is the fuel system.
                      Shouldn't the fuel rail keep some fuel for the initial start?
                      1. The fuel pressure regulator keeps the fuel from escaping through the fuel-return hose.
                      2. The check valve in the fuel pump keeps the fuel from escaping through the fuel-delivery hose.

                      If the fuel pump is bad, then it can't create enough fuel pressure quickly.

                      Is the check valve inside of the fuel pump?

                      Comment


                        #12
                        Originally posted by ForcedFirebird View Post
                        They aren't too short, note the spacing between the o-rings. They are just the newer style EV1.
                        Yeah, Bosch fuel injector 0280156372 (P/N 62417) is the *new* compatible model for 0280150714: https://www.boschautoparts.com/en/au...n?partId=62417

                        Comment


                          #13
                          The supply side is open all the way to the pump. The check valve is internal, but many people add them in-line.

                          Do you have a fuel pressure tester? If so, check pressure with car running, the turn it of and note how long it takes to bleed down.

                          john@m20guru.com
                          Links:
                          Transaction feedback: Here, here and here. Thanks :D

                          Comment


                            #14
                            Received the new fuel pressure regulator (P/N 0280160567) and completed the install today.

                            Opting for the lazy method, I was able to swap the FPRs without disassembling the intake manifold & fuel rail:

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                            Taking off the FPR with the fuel rail in place required a bit of wrestling. After removing the circular retaining clamp, I grabbed the extruding nipple part with vise-grip pliers to loosen the FPR. Then I took a flathead screwdriver and popped the FPR a few times with vertical force on its upper lip. Upon coming loose, about 1/4 cup of fuel proceeded to spill out of the fuel rail, so I had a bag ready to catch that below.

                            Old versus new FPR:

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