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TBI Fuel line sizes if i use Aeroquip stuff (or run hard line)???

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by jjlaughner, Dec 19, 2002.

  1. jjlaughner

    jjlaughner 3/4 ton status

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    What size lines will I need to run Fuel to and return from the tank to a Throttle body?
    I am guessing 1/2" to and 3/8" return (for aeroquip flexable lines)? What are the Factory hard line sizes?
    Any ideas, anyone try this, problems, etc.....
    Thanks, Jeremiah
    Here's why -the truck is rusted really bad and it needs new Fuel and brake lines. It has a return line leak because the tank straps are broke and the return line pulled away from tank.
    (Follow this last link and check out the previous owners new brake lines on the rear axle!)
     
  2. zakk

    zakk 1/2 ton status

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    i want to say 3/16 hard line, but i am pretty sure that would be wrong.
     
  3. TopOff

    TopOff 1/2 ton status

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    Holley TBI's STRONGLY recommend

    3/8" feed lines, and 5/16" return lines. They suggest the 3/8" lines and fuel pump will feed up to 450HP.

    The 5/16" return line is used to keep some kind of pressure on the pump and in the TBI itself. I haven't really figured it out yet, but that is almost ALWAYS the first thing Holley talks about when someone is having problems with the FI.

    Now to calrify - this is the Holley unit that can either be run with the COMPLETE Holley TBI - OR - the Holley TBI replacement unit from factory TBI systems.

    Additionally, I think the factory TBI run the same setup for feed lines and return lines. To get a more definitive answer, I would check with the the forums on www.thirdgen.org

    BTW: I am running a Holley TBI four barrel unit with 3/8" hard stainless brake lines, and 5/16" hard stainless return lines.

    These only see about 20 PSI at the MOST (I am currently running 12psi) on my setup with fuel-injection type flexible lines at tank, fuel pump, filter, and the last little bit before my TBI.

    Have fun.
     
  4. BurbinOR

    BurbinOR 3/4 ton status

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    What TopOff said. 3/8" supply and 5/16" return. More than enough for any street vehicle.
     

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