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V6 Fuel Line Routing

Discussion in 'Early CJ5 and CJ6 Tech' started by Jeremy Knakmuhs, Apr 20, 2022.

  1. Apr 20, 2022
    Jeremy Knakmuhs

    Jeremy Knakmuhs Jknakmuhs

    Parker, CO
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    Sep 16, 2016
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    About to start replacing the lines in my 68’ CJ5 with the 225 V6. Looking in the manual the lines appear to go over the engine. Current lines appear to be plastic and run right beside the transmission. So couple questions. Anyone have any better pictures of the factory routing? Or is there a reason to go that way, or could I run a more direct line. Curious what the pros and cons are for either. Also debating the preformed lines (picture attached). If there is a thread already covering this, please direct me. I was unable to locate one. Attached are some pictures. Thanks
     

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  2. Apr 20, 2022
    Beach66Bum

    Beach66Bum 1966 Tuxedo Park Mark IV 2024 Sponsor

    Big Island on...
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    I will get some pics on the weekend. I have a ‘66 with the Dauntless, should be the same. :)
     
    Jeremy Knakmuhs likes this.
  3. Apr 21, 2022
    colojeepguy

    colojeepguy Colorado Springs

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    There should be plastic line from the tank that runs up over the top of the trans, then it goes to a steel line at the back of the engine. The steel line runs right along the driver's side of the intake and down to the fuel pump.
     
  4. Apr 21, 2022
    Andrew Theros

    Andrew Theros Member 2023 Sponsor 2022 Sponsor

    Los Osos, CA
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  5. Apr 21, 2022
    Fireball

    Fireball Well-Known Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Pullman, WA
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    Note, mine is a '71 with a rear tank. The original poster's Jeep is a '68 with the under seat tank. I think it's pretty much the same under the hood but it will be different under the Jeep, of course. I also have a Buick V8 instead of the V6 but it's set up like a stock V6 under the hood.

    I have no idea why Jeep choose to run the fuel lines up over the engine. I guess they were trying to avoid being near the exhaust. It seems like having to suck the fuel up that high and over the hot engine is a recipe for vapor lock and I've had some issues in 90+ degree weather when chugging along at slow speeds offroad. No issues moving faster when there is some airflow under the hood. If I were re-routing mine and keeping the mechanical fuel pump, I would run them low along the frame rail up to the pump while trying to keep some distance from the exhaust.

    My under seat tank '69 is weird. By all accounts it should have the return style tank with the fuel lines over the engine. However, it has the older style non-return tank. It has a steel fuel line goes from the tank, along the crossframe to the right frame rail, up the right rail to the front of the engine compartment, across to the left side of the Jeep along the back side of the radiator crossframe, and connects to the fuel pump with a short piece of hose. Even without a return line I have never had any vapor lock issues with this Jeep. It's basically gravity feed from the tank to the fuel pump. It all looks original to the Jeep with factory bent lines and clips so either someone changed it out years ago or the factory decided to use up some old parts on this Jeep.
     
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  6. Apr 21, 2022
    maurywhurt

    maurywhurt Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Western North...
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    I believe the over-the-engine routing of the Dauntless fuel lines was first used sometime during the middle to latter part of the 1967 model year production, and was comprised of a combination of steel, plastic (or maybe some kind of vinyl?), and rubber lines.

    When I bought it, my early '67 (built in Aug. of 1966) had the fuel lines routed, starting from the fuel pump, turning down and then 90 degrees horizontally, parallel to the engine block below the driver's side exhaust manifold, then continuing toward the rear beside the transmission, and back to the tank.
     
    Last edited: Apr 21, 2022
  7. Apr 22, 2022
    jwmckenzie

    jwmckenzie Sponsor

    Boston, MA
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    This is how mine is run as well. I first tried running over the engine as described in I earlier posts thinking that I didn't want to run it along the side of the pan so close to the exhaust. It worked OK, but was having problems with what I thought was vapor lock so re- routed it as Maury described. Less piping and simple route

    BTW the problem was not vapor lock it was a sticking float.
     
  8. May 14, 2022
    Andrew Theros

    Andrew Theros Member 2023 Sponsor 2022 Sponsor

    Los Osos, CA
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    64EC70B5-66EA-4169-973B-8D350918C97E.jpeg 9EAC52AE-A1CB-4499-99B8-F4B509377030.jpeg I am going to bandwagon onto this thread, it has the same title as I was going to use before I remembered this one. Maybe will mean something to the OP as well.
    1969, 225, currently, my fuel line comes from the bottom of the tank. Right above the muffler. Never thought that was quite right, but I have seen that the muffler “should” be in the rear, under the bed.
    Planning for improving my fuel supply from PO hack to more or less correct, I found this factory looking setup in the cab.
    Is this where my fuel and return lines should penetrate the floor in the passenger cabin?
    All the replacement tanks and sending units seem to supply/return from the top of the tank.
    The pics are between the seats looking rearward. Tank on the right.
     
  9. May 14, 2022
    colojeepguy

    colojeepguy Colorado Springs

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    Yes
     
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  10. May 14, 2022
    Jeepsterjim

    Jeepsterjim Member

    Lincoln, CA
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    Long ago I spent way to much time running down what Kaiser Jeeps' "plastic" line was. It's the same material used for air brakes. Easily available at Napa by the foot in different diameters. The smaller return line is the same stuff....or at least it works....as 1/4" swamp cooler plastic line. I tested 4" pieces these Plastic lines in gas, acetone, and other stuff for 6 weeks in a sealed jar with no break down of material. Sure makes routing lines simple. I did run the lines in a kinda weaved cloth sleeve and ran them up through the frame. SO simple!
     
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