Jeep is acting very strange?

Discussion in 'KJ General Discussion' started by Victor Ray, Apr 16, 2021.

  1. Victor Ray

    Victor Ray Member

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    I am going to try this strange thing that my KJ is doing. 3.7v6 starts and runs. Sometimes not always, sometimes starts and runs very erratic. what I mean by erratic is it stumbles, then will clear up. Runs fine for a slow ride around the neiborhood, 30 mph to 35mph. The only thing thing that happened in the 15 minute was, the accelerator was very sensitive at first, attempt, did not do every time. So I thought I could live with it. so I took it home thinking the thing was fixed, wrong!!!
    Got it home was running just great, backed it in to my driveway, and it started to stumble and run like crap, stalled, restart, run, stumble and quit. Start again work the gas pedal to keep it running, stalls... Restart all over again, same scenario.
    What is the problem??
    I replaced the PCV Valve
    Replaced the AICV!
    Made sure no air leaks!
    Could it be a vacuum leak ?
     
  2. LibertyTC

    LibertyTC Well-Known Member Staff Member Moderator

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    Generally a Vac leak would cause it to run poorly consistently.
    Need to get it tested for fuel pressure (psi) readings. Key on reading, key off for 15 min reading & running reading.
    Post back the readings.
     
    David13 likes this.
  3. Victor Ray

    Victor Ray Member

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    Any ideas???????????????????
     
  4. David13

    David13 Full Access Member

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    Test fuel pressure. Could be fuel pump malfunction.

    Could also be dirty, contaminated gas. Dirty gas tank.

    Then, after that, get more complicated.
    dc

    Could be a kinked fuel hose.
     
  5. Victor Ray

    Victor Ray Member

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    Okay thanks!
    I have more symptoms.
    When running in gear, I shift to neutral, the idle drops instantly, then recovers to its normal speed?
    It is driving me crazy?????????????
     
  6. tommudd

    tommudd Moderator Staff Member Moderator

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    drops from what RPM down to what ?
    Then recovers to what RPM ?
     
  7. Victor Ray

    Victor Ray Member

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    700 t0 400 then back to 700
     
  8. Victor Ray

    Victor Ray Member

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    Almost stalls out bet never does?
     
  9. David13

    David13 Full Access Member

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    About 1971 or 72 my wife had a Volvo that did all that. Seemed like it was starving for fuel. At times.

    I looked under the hood and saw a fuel hose that was supposed to be half C shaped, but was worn and weary and went to a complete L shape. Sometimes. If I pushed on the point of the L it would revert to the C shape and run fine.

    I replaced the hose, I remember the parts guy at the Volvo dealer said, you are not going to like the price. Something like $11.46 or so. I told him whether I like the price or not, I wanted the hose.

    Ran fine after that.

    I suppose it could be a pressure leak from the fuel system anywhere along the line. Or a pinched hose. Or something else.
    dc
     
  10. Victor Ray

    Victor Ray Member

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    I will have to look it over again!
    Thanks!
     
  11. John P.

    John P. Full Access Member

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    I have had a mass air flow sensor do this (not on a jeep but a v6 ranger) same symptoms. Ended up replacing it and then it ran fine. It wouldn't hurt at all to get a can of mass airflow sensor cleaner and give it a good cleaning along with the other troubleshooting suggestions made here.
     
  12. lfhoward

    lfhoward Full Access Member

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    A dirty AIC (air idle control valve) can cause these symptoms. Remove and clean the AIC with throttle body cleaner and a gentle toothbrush, making sure the parts can move freely.

    *Edit: sorry, I just saw you replaced it in an earlier post.
     
  13. Victor Ray

    Victor Ray Member

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    Done did that!
    Replacing MAP sensor!
     
  14. bluegpguy

    bluegpguy New Member

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    I had similar problems with our KJ and replaced the Throttle Position Sensor and it ran perfect again for a long time.
     
  15. Mike Phelps

    Mike Phelps New Member

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    I had similar condition on my KJ and had to replace the camshaft sensor and the crank sensor. Runs fine now.