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Fuel Return Line To New Tank

Discussion in 'Early CJ5 and CJ6 Tech' started by Jeremy Knakmuhs, Nov 7, 2021.

  1. Nov 7, 2021
    Jeremy Knakmuhs

    Jeremy Knakmuhs Jknakmuhs

    Parker, CO
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    Searched but couldn't quite find the answer. We are replacing our fuel lines, tank and pump on our 68 CJ5 with the 226 V6. After talking with several suppliers, the new tanks do not have the port for the return line. After seeing that many have had vapor lock issues with not installing the return line, what have some of you done for the return lines? Drill and thread in a port? Different sending unit?
     
  2. Nov 7, 2021
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Medford Mass USA
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    I recall the sender with a return line uses a lock ring, not six screws. I also recall that nobody makes that tank in steel currently. MTS supplies both styles of tank in plastic and a sending unit with a return line. MTS COMPANY, L.C. - Jeep CJ/YJ Gas Tanks Tank 042, sending unit CJSU-6.

    How about having your existing tank cleaned, repaired and sealed?
     
  3. Nov 7, 2021
    Steve's 70-5

    Steve's 70-5 Active Member 2020 Sponsor

    Louisville, Ky
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    Cut the locking ring out of you old tank. Get a néw 6 hole tank, cut the 6 hole mount out and weld the locking ring in.
     
  4. Nov 11, 2021
    Jeremy Knakmuhs

    Jeremy Knakmuhs Jknakmuhs

    Parker, CO
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    Sep 16, 2016
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    Thanks for your replies. My dad already bought the new tank, so I never got a chance to look into having the existing cleaned and repaired. The original is also a 6 hole connection with the return on the opposite side of the tank. I have added a picture if that helps explain what I have going on. Jeep Tank.jpg
     
  5. Nov 11, 2021
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Medford Mass USA
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    I could be mistaken, but I would expect a Jeep that came with the 225 from the factory to have the tank with a lock ring. Possible your Jeep has been converted to the 225, or someone added the extra return line? If you have a new tank, you can safely drill a new hole for the return and solder in a threaded bung to accept the return line. AFAIK all the V6 Jeeps got the tank with a lock ring, and both fuel pickup and fuel return comes from the sender plate in the top of the tank. You sure that's a fuel return? Then you must take fuel from the bottom of the tank, through the floor. The 4-cylinder Jeeps take fuel from the bottom of the tank, and use that sender with the screws.

    Sorry I don't have an easy solution for you - other than returning the steel tank and going with the plastic tank and sender for a V6 Jeep.
     
  6. Nov 11, 2021
    jeepers1969

    jeepers1969 New Member

    Pueblo, Colorado
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    Aug 31, 2007
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  7. Nov 11, 2021
    jeepers1969

    jeepers1969 New Member

    Pueblo, Colorado
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    Aug 31, 2007
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    My 68 v6 has the tank shown with the return line coming up through the floor between body and the tank as shown in the photo. Years ago I had a 69 CJ5 v6 and it had the lock ring type sender with the integral return line. So it looks like the change in sending units took place late 68 or early 69
     
  8. Nov 12, 2021
    termin8ed

    termin8ed I didn't do it Staff Member

    Mason, MI
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    I'll throw another wrench in here. My V6 has the fuel line on the bottom of the tank and the return as well. Supply is the same as on my f head. The return fitting has a tube on the inside that points at the supply line. I've always thought it pretty smart in that it would help push any debris away from getting sucked into the supply line?:shrug:

    Mine is a funky 68/69. Has the 2 overhead electric wiper motors, no reflectors, older narrow radiator.
     
  9. Nov 12, 2021
    Fireball

    Fireball Well-Known Member 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Pullman, WA
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    Too add more info, my early '69 V6 has a the 6-screw sending unit and no return line to the tank. The tank has no return line fitting and looks original. The holes in the floor match the tank drain and output. There is snap-in plug in the floor where the return line would go.

    Either it had the 6 hole return line tank originally and somebody swapped it out, or the assembly line ran out of return line tanks and threw a 4 cylinder one in this Jeep. :shrug:
     
  10. Nov 12, 2021
    Oldpappy

    Oldpappy A.C. Fults - Curmudgeon at large 2021 Sponsor

    East Tennessee
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    I think you could drill a hole in the plate for the new 6 hole sender and install a fitting in that with JB Weld to avoid heating up the sender. It is just a drain.

    It gets pretty hot down here in the South. None of my Jeeps have a return line and I have never experienced "Vapor Lock". Not saying it doesn't happen, just it hasn't happened to me.

    I have seen enough posts on this and other forums where a determination of vapor lock is made based on a misunderstanding of what vapor lock actually is, to convince me other issues often get misdiagnosed as vapor lock.

    If the fuel lines are carefully routed to allow enough clearance around heat sources I think you can avoid the risk and not really need a fuel return line. Most older cars got by without one.
     
  11. Nov 12, 2021
    termin8ed

    termin8ed I didn't do it Staff Member

    Mason, MI
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    maybe its the drain fitting where my return is?
     
  12. Nov 12, 2021
    Oldpappy

    Oldpappy A.C. Fults - Curmudgeon at large 2021 Sponsor

    East Tennessee
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    "maybe its the drain fitting where my return is?"

    If so it is the work of someone who didn't know what else to do with it. It didn't come that way, a return line would be routed to the top of the tank.

    The drain in the tank is in a little bowl. Water from condensation settles to the bottom of the tank and the intended purpose for that bowl is to collect water before it goes down the pickup line, and the is to drain plug is so you can drain that water out of the tank.
     
  13. Nov 12, 2021
    Fireball

    Fireball Well-Known Member 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Pullman, WA
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    Here's what it looks like.

    The smaller fitting on the left is for outgoing fuel and the larger one on the right is the drain:
    [​IMG]
     
  14. Nov 12, 2021
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Medford Mass USA
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    I'm skeptical that JB Weld will hold up to continued exposure to gasoline. Since this is a new tank, I think the smart move would be to solder a threaded bung into the fuel tank where the return line currently is. No question that solder will be ok with fuel, and solder is strong - plenty strong enough for this purpose.

    McMaster-Carr - I would not bother with the nut. Instead I would make the hole so I could weakly thread the bung in, then solder. Not difficult. You may be able to reuse the fitting in your tank, or fit a new duplicate part.
     
    fhoehle likes this.
  15. Nov 14, 2021
    termin8ed

    termin8ed I didn't do it Staff Member

    Mason, MI
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    I get that but my original steel tank had a looped piece of steel line on the inside that sprayed the return at the pickup. I don't have that tank any more or would post a pic. The limited access makes me believe it wasn't added on. I'll check my other tanks and check them
     
  16. Nov 14, 2021
    Cj5dale

    Cj5dale Member

    East Tn
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    Here’s a pic of the connections on the bottom of my steel tank.

    I’ve since replaced this tank with a plastic one for now.

    upload_2021-11-14_18-28-39.jpeg
     
    Last edited: Nov 14, 2021
  17. Nov 14, 2021
    Oldpappy

    Oldpappy A.C. Fults - Curmudgeon at large 2021 Sponsor

    East Tennessee
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    The one on top with the bowl, is the drain, the one on bottom is where the fuel supply line would normally connect.
     
    Cj5dale likes this.
  18. Nov 19, 2021
    AKCJ

    AKCJ Active Member

    Fairbanks, Alaska
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    When I got my 70 it had the return line tee’d into the supply line. I think this would keep the fuel moving and help prevent vapor lock. And, avoids the problem of connecting to the tank.
     
  19. Nov 22, 2021
    ojgrsoi

    ojgrsoi Retired 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Weatherford, TX
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    My 67 came with no fuel tank. I bought one. The bottom had two plugs and the top had the 6 screws for the sender. I drilled a hole for the return near the hole for the sender so I could get a wrench on the inside for the bung. Then I routed a return line. This shows the rubber line but I would recommend a steel line if you can.
    The parts were at NAPA. Just a brass bung and an elbow with whatever you need to connect to your return line. I would recommend the return line. Also the comment above about routing away from heat is a great help too.
    I also ran an external ground. Don't know if I actually needed it but it worked with no issues. The ground wire is attached at one of the sender mounting screws and shown in the second photo.
    [​IMG]
    [​IMG]
     
    Fireball likes this.
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