Posted on 26 Comments

Do I need a return line?

No return line is necessary BUT you can use one if you desire. There are options for plumbing the system both ways.

26 comments on “Do I need a return line?

  1. If I have a high flow fuel pump with a regulator and return supplying 58psi to my fitech1200. do I need an additional return from the throttle body?
    Thanks justin

    1. When using an external fuel pressure regulator you can block the return on the throttle body.

      1. So if you run a high flow pump and regulator i will not have to use a return line.
        I planned on capping the return off my regulator. I just want to make 100% this wont cause a fuel spike
        Thank you

        1. You NEED a return regardless with an inline pump fuel system. It comes down to if you are returning from a remote mount regulator or from the built on regulator.

  2. I have a return line on my mechanical fuel pump, can I use a tee and connect the command center vent to this line?

    1. Do not tee them together. One is a vent and the other is a fuel return line. If you replace your mechanical pump with one that does not have a return line you can then use this line as a vent line.

      1. I have a mechanical fuel pump with a return line can I tee the fuel return line from my FCC to the fuel return line on my mechanical fuel pump?

        1. Your mechanical pumps return line has fuel travelling though it where as the vent on the Fuel Command Center doesn’t. They can NOT be tied together because of this.

  3. I have a 1995 Chevrolet 5.7 with a TBI I wish to use a adapter plate and put a Direct fuel injection self-learning system do I need a kit to plumb in the inlet and return fuel line? And will be FiTech injection system work with the adapter plate? Thank you Jim

    1. Our systems do work with adapter plates. You will need to feed the system with a high pressure efi pump like our 40101 fuel pump.

  4. Can you use the stock NOVA fuel tank that has a sender with a small return line on it for the EFI return line? Plan on using the external FiTech EFI pump kit.

    1. As long as you have a return port that is at least 5/16″.

  5. I would like to know if the return port on fitech throttle body is it fuel return or Vapor return line thanks

    1. The return line returns excess fuel to maintain fuel pressure in the throttle body.

      1. Is the return fuel under high pressure

        1. The return line should have virtually no pressure.

  6. Does your system come with a fitting to install in the gas tank for the return line… does the return line fitting have to be located at the top of the tank…and can the return line be an approved “soft” line? Thanks!

    1. Our kit unfortunately will not come with a fitting to put the return into the tank.

  7. 350zz4 tank in rear out of tank running aeromotive 100micron in line filter to facet external fuel pump to aeromotive pressure regulator to liqed fuel pressure gage to 40 micron aeromotive filter to 770 double pumper carb due I need a return line.

    1. All EFI fuel pumps will need a bypass fuel pressure regulator which needs a return line.

  8. What if the return/vent line from the Fuel Command center gets a shot of fuel, wouldn’t that scenario act like a p-trap and no longer vent properly? My installation would be in a 1968 Camaro and I want to get it right the first time. Thanks.

    1. To an extent you are correct but with the elevation change in the line with your setup there wont be an issue.

  9. Hi I’m going to be running your 1200hp system with a inline fuel pump would the Holley 12-800 fuel pump work well with the 1200hp throttle body and im trying to figure out what size return line I will need thanks

    1. The Holley 12-800 has the same specs as our pt#40102. Though ours is an intank pump we will be offering a drop in module with the pump shortly. Here is a link for information on it. It will retail for $349.

  10. Why does the inline fuel pump require a return to tank when the command center does not? The fuel pump in the command center is the same pump as the inline, so why cant the inline be deadheaded like the command center is?

    1. The fuel command center has a regulator inside of it which returns to itself. This allows no fuel to be sent back to the tank as it just circulates inside the command center. The inline kit MUST have a regulator to return unused fuel back to the tank.