Magnum EFI Return or Returnless? & Vacuum Regulator Question

Discussion in 'Magnum Engine Swaps' started by robcuda, Jun 1, 2018.

  1. robcuda

    robcuda FABO Gold Member FABO Gold Member

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    Hello,
    After doing some research I am not certain as to whether to run a Return or Returnless system on my stock EFI swap
    -Donor: Magnum 1997 5.9 returnless system 50psi with stock pump
    -Instead of stock pump I am using Tanks Inc, Tank, in tank pump, and adjustable regulator and adjusting to 50 psi

    Called Tanks Inc and they said just mount regulator by fuel tank, no vacuum. But I am questioning this..... When I go to Aeromotive's website they state that a adjustable regulator should be placed alongside the fuel rail with a return line all the way back to tank.

    What do you think is the best placement for regulator?

    Also, the adjustable regulator has a vacuum port, should I being using this for optimum performance?

    Thanks for your advice!
    Rob
     
    Last edited: Jun 1, 2018
  2. tonysrt

    tonysrt FABO Gold Member FABO Gold Member

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    If you want a fuel pressure gauge and the ability to regulate best to put it where it is easily accessible.
     
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    • robcuda

      robcuda FABO Gold Member FABO Gold Member

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      Thanks for the response. Accessibility to read the guage isn't a priority. I'm looking for the best location of the regulator for best performance.
       
    • TrailBeast

      TrailBeast Slightly Twisted Member

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      I would do a return for where you live, as you will get cooler fuel from the circulation.
      The regulator can be placed pretty much anywhere in the return, but don't know about the vacuum part unless it's for referencing the pressure for some reason.
      (usually referencing is for boosted applications)
      I'm sure their directions cover that.
       
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      • tonysrt

        tonysrt FABO Gold Member FABO Gold Member

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        I used the Aeromotive regulator on my gen 2 hemi with 2 4bbl carbs and didn't use the vacuum fitting, just adjusted to reduce pressure down to 6 psi for the carbs. Worked very well.
         
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        • robcuda

          robcuda FABO Gold Member FABO Gold Member

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          Hey TrailBeast, thanks for recommendation on return line to keep fuel cool. However, you mention to put regulator along Return? Shouldn't it be Before fuel rail? Help me out here please
           
        • tonysrt

          tonysrt FABO Gold Member FABO Gold Member

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          I did have a return on the carbs but had regulator on feed side.
           
        • TrailBeast

          TrailBeast Slightly Twisted Member

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          On a return system the regulator can be either before or after the fuel rail because it just regulates the pressure in the total line between the fuel pump and regulator.
           
        • robcuda

          robcuda FABO Gold Member FABO Gold Member

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          Got it. Thanks. Does the return line from engine bay back to fuel tank have to be EFI hose, or can it be standard fuel hose?
           
        • TrailBeast

          TrailBeast Slightly Twisted Member

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          Racing regs are no more than a certain amount of rubber hose in the entire line, and it isn't much.
          Maybe consider nylon 12 EFI line or steel/aluminum if wanting to pass regs.
          I ran 3/8 nylon 12 for the feed and return both, though I have no intention of racing it.
           
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          • Dubob

            Dubob Well-Known Member

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            The purpose of the vacuum reference is to keep the pressure at the injector tip at its optimum psi. Supposed to keep the spray pattern at what its designed for. Here’s an article if interested. If it were me I’d run a return for the simple fact it gives you the ability to expand its abilities down the road.


            Fuel Pressure Regulators | VaporWorx - We Give You Gas
             
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            • myduster360

              myduster360 FABO Gold Member FABO Gold Member

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              Just get an 92-94 Magnum Fuel Rail.

              Its already setup for a return line AND,,this is the best part, it includes a integral vacuum reference regulator.
              A new regulator is easily available and installs in about 2 min.

              Then all you have to do is simply run the two lines to the tank and filter and you're done.

              upload_2018-6-1_15-34-0.png
               
              Last edited: Jun 1, 2018
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              • robcuda

                robcuda FABO Gold Member FABO Gold Member

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                I guess I'm thinki
                That's something I hadn't thought of! So the vacuum reference regulator would go to my adjustable regulator vacuum input?
                 
              • myduster360

                myduster360 FABO Gold Member FABO Gold Member

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                No that's it. Just that rail. There would be no need for any other regulator. You'd use the stock fuel regulator mounted in that stock magnum fuel rail. That is all.
                Its already preset to the stock fuel pressure

                You need that rail, a fuel filter and fuel lines(fittings, ect). NOTHING else is needed to regulate fuel pressure.
                 
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                • robcuda

                  robcuda FABO Gold Member FABO Gold Member

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                  I have been reading about this and I believe my donor vehicle used voltage to the pump to address any issues of regulation. Now that I'm not using the stock fuel pump I think I will have to use vacuum to the regulator. Maybe this will be a more crude approach to regulate vs. the ECM doing it on the donor car.
                   
                • robcuda

                  robcuda FABO Gold Member FABO Gold Member

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                  Ok got it! Thanks for clarifying.
                   
                • myduster360

                  myduster360 FABO Gold Member FABO Gold Member

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                  I ran the same 92-94 Stock rail/regulator on my M1/Magnum head conversion in my Duster 360.
                  It just made the rest of the fuel system simple and readily serviceable from any parts store

                  20170401_100550-jpg.jpg
                   
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                  • tonysrt

                    tonysrt FABO Gold Member FABO Gold Member

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                    With the pressure you're running I would use EFI hose. Regular hose isn't rated for the high pressure.
                     
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                    • Bobzilla

                      Bobzilla Well-Known Member

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                      Your 1997 donor truck did not use voltage to regulate pressure. It's a returnless system with a regulator built into the fuel pump assembly in the fuel tank. Running an aftermarket regulator mounted near the fuel rail on the engine allows you to set it up exactly like the 92-94 factory regulator. Functionally, it's the same.
                      The vacuum line on the factory setup is so it has normal pressure under no load, then slightly higher pressure under heavy load, like full throttle acceleration. Not sure if your aftermarket regulator is vacuum referenced or boost referenced, but the instructions for it should clarify that.
                       
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                      • robcuda

                        robcuda FABO Gold Member FABO Gold Member

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                        Thanks for all the input guys. Gave me some different approaches that I had not thought of. Appreciate it.
                         
                      • 68coupe

                        68coupe Well-Known Member

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                        If you are using a Tanks, Inc fuel tank with an in tank pump, why would you even want a regulator? The fuel pressure regulator and pressure relief (return) is performed inside the tank. Didn't you specify your required fuel pressure to Tanks, Inc when you had them install the pump?
                         
                      • robcuda

                        robcuda FABO Gold Member FABO Gold Member

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                        The tanks inc pump is 100 psi. For my application (97 Magnum) ~48 psi is needed to fuel rail, thus a regulator is needed. I am not aware of any "in tank regulator" for a tanks inc application.