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Trouble Idling

Discussion in 'Early CJ5 and CJ6 Tech' started by Johns1967CJ5, Sep 16, 2018.

  1. Sep 16, 2018
    Johns1967CJ5

    Johns1967CJ5 Sponsor

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    She runs great when choke is half out. Soon as choke is open she stalls any suggestions
     
  2. Sep 16, 2018
    TIm E

    TIm E Aggressively average

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    The idle circuit in the 2G are tiny little passages, need to make sure those are clear. I save the clipped ends of new guitar strings as they make a nice set of varied size wire for cleaning stuff like this.

    Where are your idle mixture screws set (the two on the front of the carb base)? Good starting point is screw them in until they just barely seat, then back out 1 1/2 turns. Once idling at operating temp, screw them in until it starts to stumble, then back them out 1/4 to 1/2 turn. Vacuum gauge can be used to set idle mixture as well.
     
  3. Sep 16, 2018
    Johns1967CJ5

    Johns1967CJ5 Sponsor

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    Idle mixture are out 3/4 of a turn. How do u get to the idle jets ?
     
  4. Sep 16, 2018
    47v6

    47v6 junk wrecker! 2023 Sponsor 2022 Sponsor

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    Check your carb gasket. You may have a vacuum leak somewhere.
     
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  5. Sep 16, 2018
    TIm E

    TIm E Aggressively average

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    I would start by backing the idle mixture screws out another 3/4 turn (total of 1 1/2 turns from lightly seated).

    Page 120 in the FSM might be helpful, it explains the 2G idle system with diagrams.
     
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  6. Sep 16, 2018
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    The idle jets are behind the idle mixture screws, in the venturi of the carburetor. The conical end of the idle mixture screw fits in the jet and changes the size of the opening. To clear the jets, you can remove the screw and push a fine stiff wire (like the sugegsted guitar string) through into the venturi. If you take the carb off and turn it upside down with the throttle flap open, you can see the tips of the idle screw poking into the venturi when the screws are fully seated.
     
  7. Sep 16, 2018
    Johns1967CJ5

    Johns1967CJ5 Sponsor

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    I sprayed 1/2 can of crab cleaner down the carb while running. It runs smoothly at now 750 rpm
     
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  8. Sep 16, 2018
    Johns1967CJ5

    Johns1967CJ5 Sponsor

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    So right now she idles smoothly at 750 rpm she runs smooth at high rpms but when giving gas I'm getting a significant hesitation with a pop out of carb ?
     
  9. Sep 16, 2018
    TIm E

    TIm E Aggressively average

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    Sounds like maybe power valve or accelerator pump, those come into play on acceleration. I've seen where the little rubber cup on the accelerator pump plunger gets inverted.

    Fairly easy to check if you pull the top off the carb. You'll have to remove the choke cable and pivot screw that holds the idle cam on, but you don't have to pull the whole carb.
     
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  10. Sep 16, 2018
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    The 2G has a tapered needle, does it not? If so, I believe that's its power valve, and should not be prone to failure (once it's adjusted right). All accelerator pumps have a diaphragm of some type that fails eventually. Or it could be too lean from a vacuum leak that you've papered over at idle by adjusting the idle mixture. The engine will run very lean when it's at a constant speed, but will stumble on acceleration. Same situation, different source.
     
  11. Sep 16, 2018
    Focker

    Focker That's a terrible idea...What time? Staff Member

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    Dirty power valve. It's often overlooked even after a thorough cleaning.
     
  12. Sep 18, 2018
    Johns1967CJ5

    Johns1967CJ5 Sponsor

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    Pulled the carb top off and this is what the acc valve came out like. Shouldn't it be 1 PC?

    [​IMG]
     
  13. Sep 18, 2018
    TIm E

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    The rubber cup should be on the white plastic piece like this...


    The other spring goes down in the accelerator pump bore and the cone-shaped portion of the white plastic piece goes in the top of that spring, but be careful, that lower spring also holds a little check ball in down in there.
     
  14. Sep 18, 2018
    OzFin

    OzFin Vintage Jeep Guy

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  15. Sep 18, 2018
    TIm E

    TIm E Aggressively average

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    If you do go an order a new one from Mike's, highly suggest you get a brass float as well. Those Nitrophyl floats (with age and ethanol) can absorb fuel and give you fits. Only real way to know they have failed is to weigh them...and I have no idea what they are supposed to weigh, so I went with brass. At least if a brass one fails you can hear fuel sloshing around in it.
     
  16. Sep 18, 2018
    Johns1967CJ5

    Johns1967CJ5 Sponsor

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    You have an item number for it. I search their site no results
     
  17. Sep 18, 2018
    TIm E

    TIm E Aggressively average

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  18. Sep 18, 2018
    Johns1967CJ5

    Johns1967CJ5 Sponsor

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    Great thanks
     
  19. Sep 18, 2018
    TIm E

    TIm E Aggressively average

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    Anytime. Make sure you can see the little check ball in the inlet at the bottom of the accelerator bore John. It allows fuel to come in the inlet, but closes the inlet as the plunger comes down so the fuel is forced into the carb throat. New plunger won't help much without the check ball.

    This will definitely help your acceleration issue. Don't fret if there is still a minor stumble, fairly typical of the 2G.
     
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  20. Sep 18, 2018
    sterlclan

    sterlclan Member 2022 Sponsor

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    the boys is much better after getting the timing right hardly a stumble left in it.
     
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