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Mr1964cj5

Discussion in 'Early CJ5 and CJ6 Tech' started by Mr1964cj5, Aug 19, 2018.

  1. Aug 19, 2018
    Mr1964cj5

    Mr1964cj5 New Member

    Youngsville
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    Aug 11, 2018
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    i have a 64 cj5 with a f134 engine and it seems to run rich. I have a ya carb I believe is original. I’m assuming that the black soot stuff at the tailpipe means it’s too rich. How do I lean this out? Only one screw on carb. Any ideas?
     
  2. Aug 19, 2018
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    The one screw controls the idle mixture, nothing else. I don't know that much about the F134 carburetors, but the FSM (factory service manual) should be helpful.
     
  3. Aug 19, 2018
    Greevesman

    Greevesman Member

    Napa, Ca
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    Oct 12, 2014
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    Tim is correct about the idle screw. Another source of being rich is the float level being to high or too much fuel pressure. I had both problems. Seems like it should be a YF on a 64.
     
  4. Aug 19, 2018
    Mr1964cj5

    Mr1964cj5 New Member

    Youngsville
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    Yes it is a YF carb. Looks like the float level is only adjustable by bending the arm. Not sure if fuel pump is adjustable but did put new fuel pump on. Do you guys know if I screw in the idle jet will that lean it out
     
  5. Aug 19, 2018
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    When you are at idle speed, the idle circuit in the carburetor is active and the jet controls the idle mixture. Above idle speed, the idle circuit drops away and is supposed to do nothing. So above idle speed, the idle mixture screw has no effect on the mixture. If you are actually running on the idle circuit at idle speed and you screw it all the way in, the engine should die. If you screw it all the way in and the engine keeps running, something else is wrong in the carburetor.

    Normally you would adjust the idle mixture for best vacuum, or to "best lean idle" by screwing the jet in until the engine starts to stumble, then back out maybe 1/4 turn.
     
    Last edited: Aug 19, 2018
  6. Aug 20, 2018
    Mr1964cj5

    Mr1964cj5 New Member

    Youngsville
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    Ok guys thanks. I appreciate the feedback. Engine does start to bog down and want to stall as I screw in the idle. I guess I should try it right there. I was having trouble with black stuff on the floor from tailpipe. Put my finger in the end and have a lot of black soot on my finger.
     
  7. Aug 20, 2018
    70cj5134f

    70cj5134f Member

    East Tn
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    Aug 18, 2018
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    749
    Have u rebuilt the carb?
    Does it run ok, just black soot in pipe is u r concern?
    Are the plugs black?
    Is the choke butterfly all way open?
    Will it start cold without choke?
    Is air filter clean?
     
  8. Aug 20, 2018
    Mr1964cj5

    Mr1964cj5 New Member

    Youngsville
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    Yeah runs great. Just black soot. Haven’t checked plugs. Have to choke to start but then push it in and it will continue to run. Oil bathed Air cleaner is clean. Jeep runs really well.
     
  9. Aug 20, 2018
    Mr1964cj5

    Mr1964cj5 New Member

    Youngsville
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    7A802AC3-DC14-4E09-9FCB-E542489705AE.jpeg
     
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  10. Aug 20, 2018
    Don X

    Don X The Prodigal Moderator Staff Member 2023 Sponsor

    San Diego,...
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    You can put an fuel pressure regulator inline to control the pressure. Not sure that would help but worth considering.
     
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  11. Aug 20, 2018
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    Mr1964cj5 likes this.
  12. Aug 21, 2018
    70cj5134f

    70cj5134f Member

    East Tn
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    Take jeep out and run the $%&@ out of it for a few miles then look at plugs.
    Ever hear your dad say , gotta blow the soot out occasionally?
    Gotta tune engine by seat of pants feel ,and plugs!
    My pipe has always benn slightly black inside.
    Remember this engine is basicly WW2 tecknowlage.
    It and going to burn clean like newer cars.
    If it and broke,don't fix it.
    Sometimes I fix things till they are broke?
    Ps-what size tires are those?
     
  13. Aug 21, 2018
    Mr1964cj5

    Mr1964cj5 New Member

    Youngsville
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    7.00-15 tires
     
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