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Cylinder #3 not firing

Discussion in 'Early CJ5 and CJ6 Tech' started by gscj5, Sep 16, 2011.

  1. Sep 16, 2011
    gscj5

    gscj5 H2 Recovery Team

    Kettering, Ohio
    Joined:
    Sep 22, 2002
    Messages:
    339
    I am trying to get the CJ road worthy, started it up today and cylinder #3 is not firing. This has been an issue for a long time and I have just lived with it. The odd thing is sometimes it will kick in. I can remove the spark plug boot and it doesn't stumble, so I know that it's the culprit. Any suggestions?
     
  2. Sep 16, 2011
    lamar

    lamar Member

    greenville sc
    Joined:
    Jan 25, 2004
    Messages:
    327
    A new set of spark plug wires will probably fix it.
     
  3. Sep 16, 2011
    gscj5

    gscj5 H2 Recovery Team

    Kettering, Ohio
    Joined:
    Sep 22, 2002
    Messages:
    339
    I have tried a different wire and that doesn't seem to matter, maybe I am just buying cheap wires.
     
  4. Sep 16, 2011
    lamar

    lamar Member

    greenville sc
    Joined:
    Jan 25, 2004
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    327
    It may be the spark plug is bad. May be that the ceramic part of the plug is cracked.
     
  5. Sep 16, 2011
    gscj5

    gscj5 H2 Recovery Team

    Kettering, Ohio
    Joined:
    Sep 22, 2002
    Messages:
    339
    I have changed it out in the past, same plug and it still happens. I will pull it tomorrow and take a look and clean it and see what happens. It's just weird it's always the same cylinder. Maybe a bad head gasket causing the plug to foul?
     
  6. Sep 16, 2011
    gscj5

    gscj5 H2 Recovery Team

    Kettering, Ohio
    Joined:
    Sep 22, 2002
    Messages:
    339
    By the way, thanks for your help. I will let you know what I find out tomorrow.
     
  7. Sep 16, 2011
    PeteL

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

    Hills of NH
    Joined:
    Aug 3, 2003
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    9,754
    Try a compression test?

    Head gasket is one possibility. Take a look at the plug/cylinder first thing in the morning - residual radiator pressure can push coolant into the cylinder overnight.
     
  8. Sep 16, 2011
    Corveeper

    Corveeper Member

    Chanute, Kansas
    Joined:
    Jul 29, 2005
    Messages:
    817
    Have you tried changing the distributor cap?
    If so, take the valve cover off and have a close look at the valve springs for #3.
    I once chased a miss fire around for a few days before I finally found a broken valve spring.
     
  9. Sep 16, 2011
    Dingado

    Dingado New Member

    Joined:
    Sep 13, 2011
    Messages:
    40
    Had same problem, checked compression-five pounds less than other three- 105 should be 120, so my motors a little
    put in a hotter plug and got it out on the road to clean out the cylinder, seamed to help but still coughs once in awhile
     
  10. Sep 17, 2011
    BC3Jeep

    BC3Jeep Electric Bill

    NW Illinois
    Joined:
    Oct 8, 2009
    Messages:
    47
    Would ALSO try the "stick a screwdriver in the plug boot and see if it sparks to ground" trick before going too much further. If it sparks to ground THAT way.... suspect plug..... if NOT.... then suspect wire, distributor, points, etc.

    Another GOOD test...... start the bad boy up when it is DARK outside and, with no lights on anywhere, see if you can see residual sparks coming out of any of the ignition components......been there..... done that....
     
  11. Sep 18, 2011
    cpt logger

    cpt logger Member

    Western Colorado
    Joined:
    Feb 6, 2006
    Messages:
    108
    The compression test wil tell you alot. I would guess that #3 will be low. If so before you pull anything apart, adjust the valves. both intake & exhaust. They do get tight after awhile. Run it and test again. Good luck, and keep us informed. Thanks, Matt W.
     
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