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Can't get engine to idle

Discussion in 'Flat Fender Tech' started by ncs, Oct 1, 2011.

  1. Oct 1, 2011
    ncs

    ncs New Member

    Joined:
    Apr 2, 2007
    Messages:
    24
    48 cj2a, L head motor. The engine was rebuilt, plenty of oil pressure. No leaks except the rear main. 12 volt conversion with gm alternator. New solex carb with fuel pressure regulator set at 2 psi. I'm pretty sure the timing is correct, I set it before installing the engine and checked it with an adjustable timing light. The heat riser appears to be functioning properly. The crossover tub is hooked to the carb and the dipstick breather, but no the air filter. PCV is new and hooked up.

    The engine doesn't want to idle. With the choke on, it starts right up, but no matter how warm it gets, I can't take the choke off without it dieing. 1,600 rpm is about the lowest it will run. I'm only able to take the choke off if I hold the throttle open enough to stay at the high rpm, any lower and it just shuts off.

    The propane trick to look for a vacuum leaks wont work because the fan is blowing too much air past the engine. There's only two gaskets anyway, but the intake could be cracked somewhere out of sight.

    I'm out of ideas. What should I look at next?
     
  2. Oct 1, 2011
    Mike S

    Mike S Sponsor Sponsor

    Cameron Park Ca.
    Joined:
    Oct 6, 2009
    Messages:
    811
    Sounds like not enough fuel at idle.

    Did you do anything to the carb??
     
  3. Oct 1, 2011
    ncs

    ncs New Member

    Joined:
    Apr 2, 2007
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    The carb still has the same setting it came with. The float bowl and need valve were cleaned recently as it was sticking open and flooding. I was under the impression that they only way to adjust the solex was to change the needle and seats, which hasn't been touched yet.
     
  4. Oct 1, 2011
    garage gnome

    garage gnome Rust polisher Sponsor

    Western MA
    Joined:
    Jun 19, 2009
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    1,960
    I'd guess plugged up idle jet...
     
  5. Oct 1, 2011
    w3srl

    w3srl Jeepless in Pittsburgh Staff Member Sponsor

    Pittsburgh, PA
    Joined:
    Nov 6, 2002
    Messages:
    3,958
    :iagree:

    Do you have another carb, even an old one to try? Solex carbs are very sensitive to crud in the fuel, this is a fairly common issue.
     
  6. Oct 2, 2011
    Bill F

    Bill F Finally running

    Hillsboro NH
    Joined:
    Sep 22, 2002
    Messages:
    562
    I would try a different carb. Had the same problem with my m38 turned out to be the carb.
     
  7. Oct 2, 2011
    Old Doug

    Old Doug Member

    Joined:
    Aug 3, 2011
    Messages:
    67
    My cj2a had a crack in intake cleaned carb 3 times be for I spoted it.
     
  8. Oct 8, 2011
    ncs

    ncs New Member

    Joined:
    Apr 2, 2007
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    I've taken the intake off and looked for crack. Couldn't find any. The rectangle gasket between the intake and exhaust had a crack, but it wasn't actually leaking. I even filled the intake with water to see if there was a crack somewhere out of site. Nothing. Looks like it's got to be the carb. I've got most of five carters laying around, including one I tried to rebuild, but the cross shafts are worn down and will certainly leak air.
     
  9. Oct 9, 2011
    timgr

    timgr Jeepin' Nerd Sponsor 2019 Sponsor

    Medford Mass USA
    Joined:
    Aug 10, 2003
    Messages:
    20,179
    If it were mine, I'd take the carb apart and clean it with spray carb cleaner - Berrymans is good. Also look for vacuum leaks, ie base gasket and elsewhere. Think of it as field stripping your carburetor!
     

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