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Carter Yf Throttle Linkage Questions

Discussion in 'Early CJ5 and CJ6 Tech' started by 65CJ5 SRD, Oct 25, 2019.

  1. Oct 27, 2019
    65CJ5 SRD

    65CJ5 SRD Member

    NM
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    Yes, I used the notched gasket from the rebuild kit. I've done a general web search and there's lots of hits on Carter hesitation just off idle but nothing struck me as the culprit yet. It does not seem to have any vac leaks (I've sprayed carb cleaner around the carb and idle speed doesn't change). I've played with the idle mixture screw. It goes from running to stumble both directions and doesn't bottom out. Right now it's in the "sweet spot" as far as idle goes. Scoutpilot suggested the metering rod adjustment but I'm not wanting to open it up for that yet, and most of the web hits on this say that was not the issue (for them). Doesn't mean that's not my problem though.

    If I have it idle at 900-1000 it lessens the hesitation but I don't like the idle that high. If I have it at 700-800 which is where I'd prefer it to be, the hesitation becomes pronounced. It's fine at idle and anything above the hesitation point (just above idle). If I accelerate it slowly that seems to work but you shouldn't have to do that with it. It also seems to have trouble maintaining the idle speed I set. I set it, drive it around a little and it is usually higher than what I set it for before the test drive. Not sure if that's related to the hesitation problem as such or not. Does not seem to be a mechanical issue (like the linkage not returning to rest properly).

    It's all very frustrating at this point! So close but so far...
     
    Last edited: Oct 28, 2019
  2. Oct 27, 2019
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    The manual describes the metering rod adjustment as a cure for stumble off of idle. Do you have a manual (FSM)?
     
  3. Oct 27, 2019
    65CJ5 SRD

    65CJ5 SRD Member

    NM
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    Yes, and there are links online.
     
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  4. Oct 27, 2019
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Proper size metering rod and jet, plus adjustment are the key to proper idle and no stumble.
     
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  5. Oct 27, 2019
    PeteL

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

    Hills of NH
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    One thing I've seen a lot is the weight and or check valve/ball from the YF accelerator pump passage is missing.

    They get lost when someone is working on the carb and turns it upside down. The parts fall out and are never noticed.

    Without the check, the accelerator pump doesn't pump any gas when the throttle is cracked open.

    But, Scoutpilot is the guru on this stuff.
     
    Last edited: Oct 27, 2019
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  6. Oct 27, 2019
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Good point! Another possible problem is around the throttle shaft. If it gets worn enough a vacuum leak is created.
     
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  7. Oct 28, 2019
    scoutpilot

    scoutpilot Member

    Asheboro, NC
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    Yes. It is.
     
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  8. Oct 28, 2019
    65CJ5 SRD

    65CJ5 SRD Member

    NM
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    My BIL rebuilt the carb, and he's actually pretty good at that, but this particular carb had a lot of problems to begin with (really bad previous rebuild (some shop here in town screwed it up years ago), wrong needle and seat (from bad rebuild), missing/worn linkage parts, bent/worn throttle shaft, worn throttle bore, jammed (bent) lifter link, and on and on and on). BIL (and myself to a lesser degree) have worked through problem after problem. I think we are finally close to having it sorted out...

    Check valve/ball should be in there (I fell for that one when I opened it(!), but BIL has done these before and was aware of that but we'll check it as I'd guess is we'll have it apart again soon anyway). I got a new throttle shaft and he bushed the bore when he rebuilt it so there's no play, and metering rod and jet are original to the carb (although they could have issues from before I got the Jeep so I'll keep this in mind). I will try to recheck for vac leaks again today. I did that already but I'll do it again to try and be sure I didn't miss something.

    I'm going to take it over to BIL on Weds to go through it again. He's thinking it's running too rich fouling the plugs and that may be causing the problem, so he wants to check that. While it now sounds to me like the metering rod adjustment may be the main problem, I'll let BIL go through it all again and then if it needs that adjustment, I'll help do that so I can see how it's done.

    Thanks for the ideas. If anyone thinks of anything else let me know. I'm making a list (and will be checking it twice - ha ha).
     
    Last edited: Oct 28, 2019
    Glenn likes this.
  9. Dec 15, 2019
    65CJ5 SRD

    65CJ5 SRD Member

    NM
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    Update: Looks like major vac leaks around the throttle shaft. BIL doesn't have the kind of tooling needed to re-bush the throttle body correctly. So I finally packed up the carb and sent it off to a friend in Minnesota to work on. He has 2 degrees in mechanical engineering and a lot of know-how, plus a fully equipped machine shop. This is likely my last attempt at getting that old carb to work. I'll post the results when I get the thing back and installed.
     
  10. Dec 15, 2019
    Jw60

    Jw60 Sitting up n buckled down. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Sedalia MO.
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    Mark T. and 65CJ5 SRD like this.
  11. Dec 15, 2019
    65CJ5 SRD

    65CJ5 SRD Member

    NM
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    I saw that one before. It's a great resource! The throttle shaft/body problems are beyond my ability to fix.
     
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  12. Mar 10, 2020
    65CJ5 SRD

    65CJ5 SRD Member

    NM
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    Update: Got the carb back from my friend in MN. He fixed the throttle body bore and shaft so no more leaks there. So that's done and it helped it to hold idle a bit better. I still have the hesitation off-idle though. So tomorrow when it's cooled off I'll mess with the metering rod adjustment and raise it slightly as Scoutpilot said to try.
     
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