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return line for fuel injection on '73 blazer

Discussion in 'The Garage' started by boots, Feb 27, 2006.

  1. boots

    boots 1/2 ton status

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    Location:
    Foothills of CA (Mariposa)
    Scored a HOlley projection unit all sensors holley intake software etc etc etc, though I did have to go out and buy a fuel pump block off plate oh darn! I have a whole $10 invested in the works. Planning to put it in my '73 when/if I ever get a chance. I'm curious as to how to run the fuel return line. It's been a while since I've had a chance to work on it but I don't recall a return line on it. if there isn't how'd ya'll run your returns? My current thoughts are:

    T into the vent line that goes up to the cap
    T into the supply line between the tank and the electric pump
    weld a bulkhead fitting onto the tank itself for a fitting


    all those are assuming I'm not forgetting there was a return line off the pump
     
  2. loafer

    loafer 1/2 ton status

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    Location:
    Lyman, Maine
    Don't T into the supply line.

    I ran 3/8" ID fuel line for the supply and the return, the minimum ID for the return is 5/16". Mine is an 86, so it had a factory 1/4" ID return line, but 1/4" is too small for a high flow fuel pump and will result in back pressure at the outlet of the throttle body (not good).

    I removed the fuel tank on mine and drilled a hole in the top of the tank and installed a bulkhead fitting for the return. To be safe I sponged all the fuel out of the tank and then purged it with CO2 before I drilled it. Drilling a steel tank full of fuel vapor is a bad idea.
     
  3. HarryH3

    HarryH3 1 ton status Author

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    Georgetown, TX
    I did it on my '75 when I went TPI. Just removed the sending unit and drilled an extra hole, then added a bulkhead fitting there. I used 5/16's steel brake line to make the run along the frame from the engine back to the tank.
     
  4. boots

    boots 1/2 ton status

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    Well my tank has been out for almost 5 years in various weather conditions. Planning on using a tank prep/sealer from eastwood to recondition the insides. Heck right now I'm not even sure where my sedning unit is but I can pull one out of my '75. Drilling/welding shouldn't be much of a problem, can still purge it with CO2 or 75/25 welding gas if you think appropriate. Anything else I should do in the rear while i have the tank out? already swapping body mounts and installing hitch.
     
  5. chevyk2500hd

    chevyk2500hd 1/2 ton status

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    The bulkhead in the top of the tank is the way to go.
     
  6. BobK

    BobK 1/2 ton status

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    Location:
    Petrolia,Ontario,Canada but working in Port Huron,
    I "t'd" into the fuel filler neck.Made a "T" with a barbed fitting screwed in place.Then I ran a piece of rubber fuel line from the 5/16ths hard line to the "T"
    [​IMG]
     

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