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Intermittent "puff Puff" At Exhaust

Discussion in 'Early CJ5 and CJ6 Tech' started by TonyM, Feb 21, 2020.

  1. Feb 23, 2020
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Hills of NH
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    Aug 3, 2003
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    9,754
    F-134? You mean the accelerator pump diaphragm?
     
  2. Feb 23, 2020
    TonyM

    TonyM Member 2023 Sponsor 2022 Sponsor

    Middle Tennessee
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    Jul 30, 2017
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    Went through the carb last weekend but will do it again. Will also adjust the idle a bit more - not sure what the rpms are at idle but sounds the same, or only slight faster, as my Nissan Frontier idling at 600.
     
  3. Feb 23, 2020
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Sep 21, 2002
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    Regarding setting the timing, do you plan to correct whatever the problem is? By problem I mean the reason why you couldn't get the 5 BTDC?
     
  4. Feb 23, 2020
    70cj5134f

    70cj5134f Member

    East Tn
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    Aug 18, 2018
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    I vote idle it down, around 400 for setting carb, then play with air screw.
     
  5. Feb 23, 2020
    Focker

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

    WA
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    Aug 18, 2014
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    Sorry for the confusion, main jet in this case. Remove, clean and replace.
     
  6. Feb 23, 2020
    TonyM

    TonyM Member 2023 Sponsor 2022 Sponsor

    Middle Tennessee
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    thanks all - lots to ponder and explore

    Glenn - not 100% sure what to do about the timing. Using the proper firing order, my #1 plug wire coming out of the distributor is currently between the 5 & 6 o'clock position. I could re-install the breaker plate/points and see if I can get to 5 BTDC and then re-install the Pertronix kit BUT, in retrospect, I'm not sure that i made that much of an adjustment when I installed the kit to begin with.

    I'm going to examine the pulley again and see if there's more than one timing mark/notch. Perhaps a previous owner or mechanic made one or accidentally dinged the pulley making what looks like a mark and I missed it and marked the wrong one with chalk yesterday.

    Is it possible that a PO got into the oil pump and the gear is is "off" a couple teeth?
     
    Glenn likes this.
  7. Feb 23, 2020
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Sep 21, 2002
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    12,367
    The oil pump being off a bit is certainly a possibility, and sounds like a probability since your distributor is fairly close. It's not a huge job to get everything in the right position, just takes a bit of time and patience...i.e. do it when you're not in a rush.
     
  8. Feb 23, 2020
    durangotang

    durangotang Member 2022 Sponsor

    Not Western CO
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    Mar 17, 2010
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    My Jeep has wanted to do this same thing ever since I got it and I've just learned to live with it as it has never had a effect on performance.

    Assuming all the valves are in good shape, you may have the combination of a rich mixture and an exhaust leak somewhere before the muffler (possibly even a pinhole in the muffler). Just another thing to take a look at.
     
    Glenn likes this.
  9. Feb 23, 2020
    TonyM

    TonyM Member 2023 Sponsor 2022 Sponsor

    Middle Tennessee
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    Definitely could be something with the exhaust as well. I haven’t given that too much attention. A PO clamped a muffler of some sort (may be a proper one, may not) onto the original long pipe so everything from there back is kinda cobbled together. Been looking at re-doing everything from the manifold back but funds have been diverted elsewhere. I’ll snoop around the exhaust this week in addition to the carb and idle.

    At the end of the day I don’t have power loss or hesitation so at least I can drive around ok.
     
  10. Feb 23, 2020
    durangotang

    durangotang Member 2022 Sponsor

    Not Western CO
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    Mar 17, 2010
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    Mine is the same way and has been for the past 20k miles. I assume that I am making adjustments for compensate for worn valve guides but am unmotivated to fix it.
     
  11. Feb 27, 2020
    70cj5134f

    70cj5134f Member

    East Tn
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    I had to mess with my dizzy clamp to get it so I could get 12-14BTDC range. Took some trial and error. Running bout 10btdc now. My carb is sensitive, 1/4 turn and idle stumbles!
    Set all else first, warm engine, adj screw for high idle .
     
  12. Apr 30, 2020
    Bigdaddy13

    Bigdaddy13 Member

    So.Cal
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    Nov 19, 2019
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    556
    My CJ2A's f-head did the same thing. never could sort it out and it ran like a sewing machine for 2 years that I owned it. :)
     
  13. Apr 30, 2020
    TonyM

    TonyM Member 2023 Sponsor 2022 Sponsor

    Middle Tennessee
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    Jul 30, 2017
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    yeah...I got the idle down a bit and adjusted the fuel/air mix and the "puff puff" has all but disappeared. She's running great, though I haven't been able to take it out for too long lately.
     
    Glenn and Bigdaddy13 like this.
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