Another Fuel Starvation Thread

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  • DTFE30
    E30 Addict
    • Feb 2011
    • 471

    #1

    Another Fuel Starvation Thread

    I did some searching around and it didn't yield any specific results. I have an early model 325e with S50 swap. Last two times at the track I have been having a problem with the car sputtering hard after right turns. They werent long drawn out turns by any means like most people are saying. The car will sputter after I have gotten through the corner and onto the strait. This happens after I have only used about 3.5 gallons of fuel. I have the dual pump setup and I am wondering if the transfer pump could have gone bad. Can the high pressure pump run the car alone? The high pressure pump also is a little noisy. Any feedback would be great!
  • E30Gus
    Mod Crazy
    • Jun 2008
    • 781

    #2
    Crossover tube in the fuel tank may be clogged. That was my problem with a nearly full tank.

    Comment

    • jlevie
      R3V OG
      • Nov 2006
      • 13530

      #3
      It sputtering with that little fuel used sounds like a weak or dead transfer pump. Though a rusty tank is also a possibiltiy.
      The car makes it possible, but the driver makes it happen.
      Jim Levie, Huntsville, AL

      Comment

      • BAR51
        Advanced Member
        • Nov 2011
        • 105

        #4
        Originally posted by E30Gus
        Crossover tube in the fuel tank may be clogged. That was my problem with a nearly full tank.
        Has anyone found an efficient way to clean out a clogged crossover tube?

        Comment

        • E30Gus
          Mod Crazy
          • Jun 2008
          • 781

          #5
          Originally posted by BAR51
          Has anyone found an efficient way to clean out a clogged crossover tube?
          The tube is removeable (if you're lucky) but it is clogged due to all the crud in the tank so the tank needs to be cleaned or replaced.

          Comment

          • DTFE30
            E30 Addict
            • Feb 2011
            • 471

            #6
            Thanks for the input!

            Comment

            • Wh33lhop
              R3V OG
              • Feb 2009
              • 11705

              #7
              My car has run with a dead transfer pump for years; I have just had horrible starvation issues when below a half tank. I replaced it the other day and fuel starvation has gotten much better.

              I'd check if your transfer pump is operational. Doesn't take that long to access it.
              paint sucks

              Comment

              • DTFE30
                E30 Addict
                • Feb 2011
                • 471

                #8
                Checked last night and it is in fact dead. Just ordered a new one. Thanks!

                Comment

                • Beej '86 325es
                  R3VLimited
                  • Feb 2004
                  • 2639

                  #9
                  I had my first track day yesterday, and I noticed this problem on my 2/86 build S50 car with 3/8 of a tank remaining.

                  Where is the cross-over tube located?

                  Also, I'll check my transfer pump, but if the main external pump is still able to supply the engine under normal conditions, why would it matter if the transfer pump is dead? Maybe I don't understand the 2-pump setup correctly...they both draw through the transfer pump, correct?
                  -Brandon
                  '86 325es S50
                  '12 VW GTI Autobahn DSG
                  '03 540i M-Sport (sold)
                  '08 Jeep SRT-8 (sold)

                  For sale:
                  S50 TMS chip for Schricks

                  Comment

                  • jlevie
                    R3V OG
                    • Nov 2006
                    • 13530

                    #10
                    The transfer pump is there to feed the high pressure pump. With the tank mostly full the high pressure pump is able to suck in fuel. But as the tank gets low that work becomes greater than what to pump can do. The transfer pump unloads the input side of the high pressure pump.
                    Last edited by jlevie; 07-30-2013, 06:36 AM.
                    The car makes it possible, but the driver makes it happen.
                    Jim Levie, Huntsville, AL

                    Comment

                    • markseven
                      R3V Elite
                      • Sep 2006
                      • 5327

                      #11
                      Keep the tank more than half-full on non-NASCAR circuits ;)
                      I Timothy 2:1-2

                      Comment

                      • Cephas
                        E30 Modder
                        • Apr 2012
                        • 878

                        #12
                        Originally posted by markseven
                        Keep the tank more than half-full on non-NASCAR circuits ;)
                        Easier said than done at 8mpg!

                        :nice:

                        Comment

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