1. Registration trouble? Please use the "Contact Us" link at the bottom right corner of the page and your issue will be resolved.
    Dismiss Notice

Newbie With Carb Issues

Discussion in 'Early CJ5 and CJ6 Tech' started by Hunter92040, Oct 18, 2021.

  1. Oct 18, 2021
    Hunter92040

    Hunter92040 New Member

    San Diego
    Joined:
    Sep 30, 2021
    Messages:
    7
    Before I get deep into my auger project, I want to get the jeep in tip-top shape. The only mechanical issue is difficulty starting. Without starter spray, it won't start. If I use starter spray, it fires right up and runs pretty good (might idle a little rough, not much though). Looks like the 1970CJ5 has an unnumbered Rochester carb (see pix below). I'm think about just rebuilding the carb.
    What is everyone thoughts on a possible fix to the starting?
    Should I just rebuild it?
    Any suggestions on identifying the correct rebuild kit?
    Any info is appreciated.
    Thanks,
    Gene
    IMG_1502 j.jpg IMG_1503.jpg IMG_1504.jpg IMG_1505.jpg
     
  2. Oct 18, 2021
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member

    Bozeman, MT
    Joined:
    Jul 18, 2013
    Messages:
    5,593
    Looks like a 2gc carb...is the automatic choke functional? Maybe the accel pump isn't functioning? Easy rebuild....check out Mike's carburetor vids and parts.
     
  3. Oct 18, 2021
    boopiejones

    boopiejones I can’t drive 55

    California east bay
    Joined:
    Mar 16, 2020
    Messages:
    545
    [​IMG]

    If it’s hard to start without carb spray, it’s likely you’re not getting enough fuel, or getting too much air, or a combination of both. is this image your choke in its fully cold position? If so, it looks to me like it needs to be adjusted to close a bit more and your fast idle cam needs adjustment as well, which should help with cold starts.

    If that doesn’t work, it’s possible you have some clogging inside the carb. 2G carbs are very easy to rebuild if needed.
     
  4. Oct 18, 2021
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
    Joined:
    Aug 10, 2003
    Messages:
    23,596
    I would start with fuel supply, and rule out a weak fuel pump or clogged plumbing to the carburetor. The FSM has a spec for the pressure that the fuel pump should deliver. Fuel pump / vacuum gauges are cheap and something you should have. Though it's not specified, I would also test for volume when cranking - should deliver a good cupful in say 15-20 seconds.

    Example: https://www.amazon.com/Actron-CP780...06V2BS2/ref=pd_lpo_3?pd_rd_i=B0006V2BS2&psc=1

    Choke / fast idle and accelerator pump should also work. Do you have the FSM?
     
  5. Oct 18, 2021
    Oldpappy

    Oldpappy A.C. Fults - Curmudgeon at large 2022 Sponsor

    East Tennessee
    Joined:
    Feb 8, 2021
    Messages:
    1,620
    If it runs good once started I too suspect the choke is not closing, and possibly the accelerator pump diaphragm is shot.

    They are easy to clean and rebuild, and the 2G is one of the most reliable carburetors ever made.
     
    dnb71R2 likes this.
  6. Oct 18, 2021
    dozerjim

    dozerjim Member

    western New York
    Joined:
    Nov 22, 2010
    Messages:
    965
    X2....
     
  7. Oct 18, 2021
    peter

    peter Member

    Roseville, CA.
    Joined:
    Aug 26, 2008
    Messages:
    161
    After the last few years tinkering with my Rochester 2g and 3 rebuilds, the last one done by a professional shop, I decided to just find another one. Not easy as they just are not available. After months of looking I did find a restored one in SoCal and pulled the trigger. Installed and first test drive is running more smoothly than before and hopefully problem solved. As mentioned, first check for any vacuum leaks and fuel delivery. My manual choke is critical for cold start ups so make sure the choke is working correctly. Then do not hesitate to rebuild the carb and see how it goes. Just could not justify the cost of fuel injection or a different type of carb with adapters so i chose to find another Rochester 2G.
    Good luck. Peter
     
  8. Oct 19, 2021
    Hunter92040

    Hunter92040 New Member

    San Diego
    Joined:
    Sep 30, 2021
    Messages:
    7
    Thanks for all the input. Like I said, I'm a major newbie but I love learning. Is this the choke that is open too much?
     

    Attached Files:

  9. Oct 19, 2021
    boopiejones

    boopiejones I can’t drive 55

    California east bay
    Joined:
    Mar 16, 2020
    Messages:
    545
    Yes. That is the choke valve, and it should be closed more. Most applications call for a gap of about 1/16” when cold. and the fast idle cam should be turned further counterclockwise to allow a faster idle at startup. That said, i don’t know if the engine was cold and the choke had been “set” when you took the picture. With the engine cold and not running, if you step on and release the gas pedal the idle screw will pull away from the fast idle cam and the choke should “set” itself… Assuming the choke thermostat is properly adjusted, the “set” involves the choke valve closing a bit more and the fast idle cam moving so the idle screw sits “higher” on the cam.

    If the engine is cold and you step on the gas but the choke valve and fast idle cam don’t move enough, the typical adjustment would be to turn your choke thermostat counterclockwise.

    here’s a link to the 2G adjustment instructions from mikes carburetor parts, which I found extremely helpful:https://www.carburetor-parts.com/assets/instructionsheets/K427.pdf
     
    Last edited: Oct 19, 2021
    FinoCJ likes this.
New Posts