Engine Sputters/Hesitates at 2000 RPM

Discussion in 'Mopar Performance Issues' started by MuuMuu101, May 8, 2018.

  1. MuuMuu101

    MuuMuu101 Well-Known Member

    Messages:
    1,729
    Likes Received:
    126
    Joined:
    Jul 6, 2012
    Location:
    SoCal
    View My Photos
    Local Time:
    4:17 PM
    Hey all, so the temperamental Dart decided to act up again. 68 Dart 408, Holley 800cfm dp, Holley blue fuel pump stock tank, large cam, MSD Ready-to-Run distributor. This one has started about a month ago before I got my exhaust done.

    At first it was just something that would happen when I would enter on the freeway, while accelerating the engine would "sputter" and hesitate climbing over 2000 rpm, but eventually make it and be fine for the rest of the trip.

    Overtime the sputtering on acceleration got better when going on the freeway, but started to occur more so shortly after start up. Basically it would sputter and buck causing the car to rock back and forth and eventually shut off. If I restarted it and let it warm up again, it would eventually cooperate and drive normally. This occurred the morning of Spring Fling (60'sF) and after one restart, it made its way 60 miles to the show. On the way back it was much warmer (high 80'sF) and didn't have any problems.

    I started the car two weeks ago and now the problem has escalated severely. Now the car will not drive above 2000 RPM and will not drive up a hill. It's idling a little higher now (1000-1100 rpm), where it used to be at 800-900 rpm before. If I rev it in Neutral, it will go to 3500 before sputtering a little but will still climb higher.

    Any ideas on how to remedy this or where to start checking? I thought it may be a fuel issue, maybe a fuel filter is clogged? Carb needs cleaning or is clogged? Maybe spark plugs need to be replaced? Hopefully it's an easy fix as I don't really want to spend money on this. It kind of sucks this happened as I have no time for the next 5 weeks due to me finishing my master's and at the end of June or early July, I was going to change the entire fuel system for efi (Holley Sniper/Fitech, new lines, Tanks Inc EFI tank, and Stealth Aeromotive pump).

    Anyways, let me know your thoughts. Hopefully I can spend an hour here or there to try to remedy it.
     
  2. teringer

    teringer ase master hall of fame

    Messages:
    675
    Likes Received:
    86
    Joined:
    Feb 22, 2011
    Location:
    kenly nc
    Local Time:
    6:17 PM
    sounds like the choke is not opening all the way or sticking
     
    • Like Like x 1
    • roccodart440

      roccodart440 Well-Known Member

      Messages:
      4,678
      Likes Received:
      3683
      Joined:
      Apr 19, 2010
      Local Time:
      7:17 PM
      definitely sounds fuel related.
       
    • Murray

      Murray FABO Gold Member FABO Gold Member

      Messages:
      484
      Likes Received:
      184
      Joined:
      Apr 19, 2010
      Location:
      San Jose, California
      Local Time:
      4:17 PM
      I'm not very good on Holley's but it sounds reluctant to kick in high speed circuits. Power valve? Dirt in carb? Air bleeds?
       
    • MuuMuu101

      MuuMuu101 Well-Known Member

      Messages:
      1,729
      Likes Received:
      126
      Joined:
      Jul 6, 2012
      Location:
      SoCal
      View My Photos
      Local Time:
      4:17 PM
      I was thinking about this last night and how it's acting and I sort of agree with you. I have a manual choke cable and now that I think about it, it was sticking out farther than usual. I think I'm going to try readjusting it or disconnecting the manual choke cable and see if it does anything.

      I was too, but when I checked my fuel pressure last night, it was at 6.5 psi at idle. Does fuel pressure lower while driving?
       
    • jimjimjimmy

      jimjimjimmy lobsterman FABO Gold Member

      Messages:
      3,877
      Likes Received:
      673
      Joined:
      Nov 2, 2010
      Location:
      p. e. i.
      View My Photos
      Local Time:
      8:17 PM
      pickup coil or rusted or broken advance springs .
       
    • AJ/FormS

      AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

      Messages:
      13,714
      Likes Received:
      3312
      Joined:
      Jan 19, 2014
      Location:
      South-Central Manitoba,Canada, 900ftelevation
      View My Photos
      Local Time:
      6:17 PM
      My guess is you have Multiple fuel mixing problems.
      Try and isolate it to a particular part of the foot pedal travel; ie ; less than 1/4 throttle, or 1/4 to 1/2 etc.
      These are the things I would do, and in the order I would do them;
      1) The first thing I would do is walk around to the back of the car and stick my finger in the tailpipe and take a soot swipe. I wanna know if it's rich or lean. Then I would start it up and listen to it idle. You can tell an awful lot about the low-speed circuits, the plugs, and the timing by how it idles.
      3) Next I would verify the timing systems are all working properly, cuz that is so easy to do.
      4) Then,I would verify the thermostat is maintaining it's minimum operating temp.and that you are not trying to run it too cold. My 367 likes 205*
      5) And that the choke is fully off.
      7) Then I would search for a vacuum leak. Including everything plumbed to the intake,the base gasket,the port runners, and the valley side.
      8) Next I would blow out the low-speed air-bleeds.
      10) If you have driven it and forgotten to shut off the choke, then I would replace the plugs.
      11) I would make sure the secondaries are fully closing to whatever stop-system you are using.
      12) If you have a mechanical cam, I would lash the valves, and add .002 to whatever your specs are.
      Now we are ready to get into it;Next I would
      15) check the float level
      16) verify the gas is pure fresh gas
      17) verify the T-port sync.
      18) that the accelerator pump is properly adjusted, and not dribbling.
      19) and that the PV is not leaking
      20) And if I still hadn't found it, I'm doing a compression test.

      You can stop as soon as you find the issue
      But if you swiped the tailpipe and found it black, then I would go straight to #8 EDIT I meant #5, and replace the plugs.Then check the oil; make sure it is all pure oil; smell it and rub it between your finger and thumb. Then
      Roadtest it, and if you have to; go back to #1,lol.
       
      Last edited: May 11, 2018
    • MuuMuu101

      MuuMuu101 Well-Known Member

      Messages:
      1,729
      Likes Received:
      126
      Joined:
      Jul 6, 2012
      Location:
      SoCal
      View My Photos
      Local Time:
      4:17 PM
      I'm 99% sure I fixed the problem. I went to remove the air cleaner assembly and when I flipped it upside down, I noticed scratches on the side with the manual choke. I looked at the choke and it was barely half open. I went to the driver's seat and pushed my manual choke cable and came back to find that it didn't move nor did it have the power to fully open the choke. So, I removed it and started the car up. I let it warm up for a bit and man... it felt like an all new car! I took it for a cruise up a hill, merged on the freeway, and even did a WOT pull. That stupid cable was probably the reason why I felt like it was running rich (smelled like gas) and getting 6-8 mpg.
       
    • j par

      j par Well-hung Member

      Messages:
      8,810
      Likes Received:
      2635
      Joined:
      Jul 2, 2014
      Location:
      Portland Oregon
      View My Photos
      Local Time:
      4:17 PM
      You know that's exactly what I was thinking....
       
    • AJ/FormS

      AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

      Messages:
      13,714
      Likes Received:
      3312
      Joined:
      Jan 19, 2014
      Location:
      South-Central Manitoba,Canada, 900ftelevation
      View My Photos
      Local Time:
      6:17 PM
      OOps I got three and five mixed up
       
      • Agree Agree x 1
      • j par

        j par Well-hung Member

        Messages:
        8,810
        Likes Received:
        2635
        Joined:
        Jul 2, 2014
        Location:
        Portland Oregon
        View My Photos
        Local Time:
        4:17 PM
        I missed that too..
         
      • racerhog

        racerhog RacerHog likes his Mopars

        Messages:
        1,010
        Likes Received:
        254
        Joined:
        Nov 18, 2008
        Location:
        Monrovia SO-CAL
        Local Time:
        4:17 PM
        The Simplest things some times.....
         
      • jimjimjimmy

        jimjimjimmy lobsterman FABO Gold Member

        Messages:
        3,877
        Likes Received:
        673
        Joined:
        Nov 2, 2010
        Location:
        p. e. i.
        View My Photos
        Local Time:
        8:17 PM

        oh I missed in the op where it was running rich and got 6-8 mpg disregard post 6