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Hard Starting 71

Discussion in 'Early CJ5 and CJ6 Tech' started by fabrication, Aug 2, 2007.

  1. Aug 2, 2007
    fabrication

    fabrication New Member

    Chandler Arizona
    Joined:
    Oct 13, 2006
    Messages:
    29
    My 71 jeep starts just fine when it is cold but after it warms up and I try to start it back up I can smell fuel and the battery goes dead trying to get it started. It is a v-6 stock motor with a Holly 2 barrel that was just rebuilt. It also has a new electronic ignition, new plug, wires and fuel pump. I have checked the float sighting window and it seems not to be stuck. I have adjusted the fuel mixture with no luck. The jeep runs great except for a slight backfire when down shifting. All I use my jeep for is hunting and my elk hunt starts in a month and I don't want to get stranded. Just when I think I have it figured out I get stranded. Any help would be appreciated. Thanks Lee
     
  2. Aug 2, 2007
    BlueFlu

    BlueFlu past owner of some ecj5's

    Hermitage, TN
    Joined:
    Jan 21, 2004
    Messages:
    1,552
    1st thought was a timing issue.
    2nd maybe vapor lock.
     
  3. Aug 2, 2007
    zila

    zila I throw poop

    Rock Springs,...
    Joined:
    Oct 6, 2003
    Messages:
    1,201
    I am not a big fan of Holley carbs.. I have one on my 304 and it floods when offroad quite often.. If I were you I would check the choke and see if it is returning to normal after start up. Then check the float level.. You check the float level with the engine running and the float check screw removed.. Adjust the float until fuel barely comes out of the hole..

    The second thing I would look at is the power valve.. It may be leaking fuel by and causing the flooding. I rebuilt my Holley and the kit had the wrong type power valve and gasket in it.. I had a terrible time as you did until I figured it out.

    I am in the process of replacing my Holley with a Motorcraft 2100..
     
    Last edited: Aug 2, 2007
  4. Aug 3, 2007
    w3srl

    w3srl All-around swell dude Staff Member

    Port Orange, FL
    Joined:
    Nov 6, 2002
    Messages:
    4,275
    Vapor lock gets my vote.

    I'd check the fuel lines to be sure they aren't too close to the exhaust, and also that you don't have too much rubber hose in the line. A restricted fuel flow (plugged up pick-up in the tank) a plugged fuel filter or a weak fuel pump can contribute to vapor lock.
     
  5. Aug 4, 2007
    Bucket of Bolts

    Bucket of Bolts Broke Member

    Dinuba, Ca.
    Joined:
    Jun 3, 2006
    Messages:
    60
    If you have already determined you have good spark, I say vapor lock too. I had a similar issue, but mine would start if i held the throttle wide open. I talked to a guy who had built a few race carbs for us in the past. He told me it has become a pretty common problem in recent years with new gas formulas. The gas seems to be boiling at a lower temp, and when the engine is shut off hot, the carb heats up without air and fuel going through it and boils the fuel out of the carb bowl and into the intake. Not a problem with fuel injection because of the higher fuel preasure that they require, probably better fuel atomization on those engines. But a problem for carburators, Some of his customers are having to do modifications to insulate the carburator. phenolic spacers heat shields etc. In my case, this is exactly what was happening, infact I could hear the fuel boil and watch it drip into the intake manifold. an extra thick carb gasket cured it for me. I'm not sure this is you problem, but wanted to pass the info on.
     
  6. Aug 4, 2007
    fabrication

    fabrication New Member

    Chandler Arizona
    Joined:
    Oct 13, 2006
    Messages:
    29
    It was vapor lock. I installed an extra thick carb gasket and that helped a little but the cure was placing an 1/8" phenolic piece under the front of the carb where the float bowl is located. I held it in place with a piece of safety wire. Thanks for all the help.
     
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