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Fixed: V6 Cutting out at cruising speeds?

Discussion in 'Early CJ5 and CJ6 Tech' started by sparky, May 14, 2006.

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  1. May 14, 2006
    sparky

    sparky Sandgroper Staff Member Founder

    Perth, WA
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    Re: V6 Cutting out at cruising speeds?

    I was thinking about that one tonite after Brannon suggested a fuel problem. But no, notchet.
     
    sparky, May 14, 2006
    #21
  2. May 14, 2006
    jpflat2a

    jpflat2a what's that noise?

    Hermosa, SD
    Joined:
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    Re: V6 Cutting out at cruising speeds?

    Sparky, don't take this personally, but new parts can be bad/go bad ...
    I wish I had a dollar for every do-it-yourself tune-up Jeep that found it's way to the shop.....
    I had to listen as the owners would swear that it couldn't be this or that, and that they had replaced everything already...
    for instance, very easy to crack the porcelain of the plug when tightening the spark plug; some folks just install them without checking the gap....
    I always took that into consideration, but the truth is, you can't overlook anything....when diagnosing, you have to start from scratch....
     
    jpflat2a, May 14, 2006
    #22
  3. May 14, 2006
    sparky

    sparky Sandgroper Staff Member Founder

    Perth, WA
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    Re: V6 Cutting out at cruising speeds?

    Not taking it personally, that's why I threw it out there.
     
    sparky, May 14, 2006
    #23
  4. May 14, 2006
    SRedinger

    SRedinger Member

    Now Eugene, Oregon
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    May 14, 2006
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    Re: V6 Cutting out at cruising speeds?

    Sparky, I have had this problem when the valve springs were too soft. This can happen with aged springs that have not even run.
    The engine can run with out a load and rev. but lacks the torque to keep running under a load. Sometimes called 'floating valves'. The valves do not close fast enough to provide higher rpm torque under a load. Under the right load and rpm the engine will stall due a fast drop in manifold vacume because just a little bit of cylinder gases are leaking back into the intake manifold out of the four stroke cycle. This is because the valves (intake esp and also exhaust) are not closing fast enough and long enough. Lack of vacuum with an aspirated engine, means that the engine does not get enough air and fuel--- and then it stalls. This lack of manifold vacume also affects the vacuum dist timing as well-- retarding the timing, causing more cylinder gas to leak into the intake and futher making the situation worst. Put a vacuum gadge on the engine that you can read under different driving conditions and see of you have a rapid drop in vacume in third gear.
     
    SRedinger, May 14, 2006
    #24
  5. May 14, 2006
    jpflat2a

    jpflat2a what's that noise?

    Hermosa, SD
    Joined:
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    Re: V6 Cutting out at cruising speeds?

    :oops:
    banging head against wall
    good idea, teeing in the vac gauge
    I shoulda thought of that....:oops:
     
    jpflat2a, May 14, 2006
    #25
  6. May 14, 2006
    MOP

    MOP Active Member

    Pullman, WA
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    Re: V6 Cutting out at cruising speeds?

    Welcome SRedinger! I see that is your first post. Maybe the best first post I have ever seen here.
     
    MOP, May 14, 2006
    #26
  7. May 14, 2006
    sparky

    sparky Sandgroper Staff Member Founder

    Perth, WA
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    Re: V6 Cutting out at cruising speeds?

    Hmm. So would it manifest itself suddenly as this has or would it be a more gradual onset?

    Where would I get a vacuum gauge? FLAPS?

    FWIW, I know I have one bad exhaust valve in my right bank.
     
    sparky, May 14, 2006
    #27
  8. May 15, 2006
    jzeber

    jzeber Well-Known Member 2022 Sponsor

    Morgan Hill, Ca
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    Re: V6 Cutting out at cruising speeds?

    I had the same thing happen to me. I would get to a certain speed and the darn thing would just shut down. I changed the usual culprits, fuel filter, fuel pump etc....I finally tracked it down to something very simple. When I was at the Rubicon I thought I turned the idle on the carb up for the altitude. Turned out I adjusted the choke screw a little bit. When I would get to a certain speed the wind would catch the choke and shut completely thus not enough air and way too much fuel. Easy enough fix, I just backed out the adjustment screw and it has never done it again.

    Just my $.02!
     
    jzeber, May 15, 2006
    #28
  9. May 15, 2006
    termin8ed

    termin8ed I didn't do it Staff Member

    Mason, MI
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    Re: V6 Cutting out at cruising speeds?

    Did you let the jeep sit for any length of time with the carb exposed?
    Just asking because Wimpy did similar things. In low range it would run fine. But as soon as I tried getting in 2nd gear in high range it bogged right down. Turned out I had spiders or something spinning a little cocoon inside one of the passages.

    Reading Sredingers post, did you ever change the timing belt when you did the oil pump? might the belt have slipped a tooth?
     
    termin8ed, May 15, 2006
    #29
  10. May 15, 2006
    sparky

    sparky Sandgroper Staff Member Founder

    Perth, WA
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    Re: V6 Cutting out at cruising speeds?

    I'm gonna check the carb.

    Re timing chain: I just slapped a new, to this Jeep, stock, oil pump in. No need to touch the timing chain. If it's slipped a tooth I'd be surprised. I put an Edelbrock Double roller in last fall so it's new. As Jpflat2a said though, new parts aren't always good.
     
    sparky, May 15, 2006
    #30
  11. May 15, 2006
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Re: V6 Cutting out at cruising speeds?

    As I was reading the posts I was thinking valve issues, whether it be the springs or bad valves in general. Especially since you know you have a bad exhaust valve.
     
    Glenn, May 15, 2006
    #31
  12. May 15, 2006
    sparky

    sparky Sandgroper Staff Member Founder

    Perth, WA
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    Re: V6 Cutting out at cruising speeds?

    Just seems weird it would be so sudden and coincide with the work I've done on the distributor.

    I'm not saying that it couldn't be. Just baffles me the timing of it all.
     
    sparky, May 15, 2006
    #32
  13. May 15, 2006
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Re: V6 Cutting out at cruising speeds?

    I agree, it's enough to make you scratch your head and wonder what the.........?
     
    Glenn, May 15, 2006
    #33
  14. May 15, 2006
    sparky

    sparky Sandgroper Staff Member Founder

    Perth, WA
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    Re: V6 Cutting out at cruising speeds?

    Thing is I even commented to my friend working on it with me that I was thinking that my distributor work was a red herring and throwing me off what the real problem was.
     
    sparky, May 15, 2006
    #34
  15. May 15, 2006
    jpflat2a

    jpflat2a what's that noise?

    Hermosa, SD
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    Re: V6 Cutting out at cruising speeds?

    would advise checking engine vac before proceding with any tear down.
    the vac readings will confirm/deny most valve train/timing issues.
    should be able to get at FLAPS.
    and there should be several plugged, unused ports at the rear of the intake manifold to hook the vac gauge up to
     
    jpflat2a, May 15, 2006
    #35
  16. May 15, 2006
    sparky

    sparky Sandgroper Staff Member Founder

    Perth, WA
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    Re: V6 Cutting out at cruising speeds?

    As I said, I already know I have a bad exhaust valve in the right bank. I need to fix that among other things. So it's gonna be torn down soon here anyway. Would be good to confirm what this issue is though before tearing down.
     
    sparky, May 15, 2006
    #36
  17. May 15, 2006
    jpflat2a

    jpflat2a what's that noise?

    Hermosa, SD
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    Re: V6 Cutting out at cruising speeds?

    this might help
     
    jpflat2a, May 15, 2006
    #37
  18. May 15, 2006
    sparky

    sparky Sandgroper Staff Member Founder

    Perth, WA
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    Re: V6 Cutting out at cruising speeds?

    I've got one, didn't think of it though. :D

    Thanks!
     
    sparky, May 15, 2006
    #38
  19. May 15, 2006
    Hippo393

    Hippo393 Jeepless

    Charlotte, NC
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    Re: V6 Cutting out at cruising speeds?

    Any chance you have vacuum-activated wipers? That way you could run w/ 'em on and see if they behave out of the ordinary when the engine probs resurface.
     
    Hippo393, May 15, 2006
    #39
  20. May 15, 2006
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Re: V6 Cutting out at cruising speeds?

    Thinking about the fact you know an exhaust valve is bad makes me wonder if a vacuum check would do much good.
     
    Glenn, May 15, 2006
    #40
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