Engine stays running only if the key is held in the start position ....

1968 -1970 Mopars

  1. Cranky

    Cranky Banned Staff Member FBBO Gold Member

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    As soon as you release the key to the run position it dies. Didn't someone just post about that happening recently? If there was, I can't find it now. Anyways, did a lot of work on this car a little over a year ago but it was all mechanical and no electrical as I'm shade blind and faded wires only make it worse for me. The car also has no ballast resistor in the system and still has a point system on it. The car came for a carb issue but the carb seems to be decent idling and revving up even right after firing it up cold. Yeah, I hot wired it.

    I replaced the ignition switch with a known good one that I had stuffed away and the car does the same thing. Dies when you release the key. The under hood wiring on this thing SUCKS!! It even has house type wire nuts on it. Told him he needs to buy a new under hood harness as this one is junk (dried and hard as rocks) but he wants to get it running as is for now. He did say it's been running fine until recently. The points don't seem to be fried because I just started it and ran fine....and the battery is only 12.3v.....

    IMG_20201004_151751630.jpg IMG_20201004_151817961.jpg IMG_20201004_151854721.jpg IMG_20201004_151928641.jpg IMG_20201004_151906783.jpg
     
  2. dadsbee

    dadsbee FBBO Gold Member FBBO Gold Member

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    That IS the issue.. run goes through the ballast. If you don't have one jumper the wires and I bet it keeps running. Just don't leave it that way...
     
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    • Cranky

      Cranky Banned Staff Member FBBO Gold Member

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      He says it was running fine like that and then it started having a low speed miss and then it wouldn't start up and stay running anymore. He was going to bring it to me for what he thought were carb issues and that's when it wouldn't stay running. I only jumped it to see how the carb was acting but it seemed fine sitting here but haven't run it on the road.....just sitting and didn't do that for more than a couple of minutes.
       
    • dadsbee

      dadsbee FBBO Gold Member FBBO Gold Member

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      So the wiring from the run position, that should be going through the single ballast for the points distributor, has fell off or burned off somewhere..
       
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      • Cranky

        Cranky Banned Staff Member FBBO Gold Member

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        I don't get how it was running before....since there is no ballast resistor on the car at all! When I was working on it the last year or so ago doing the front end etc, it ran fine but never paid any attention to it having one or not but it had a different carb. He said he replaced the carb because it started leaking. Well, what can I say. He knows construction and not cars. Electrical systems is my achilles heel.
         
      • oldbee

        oldbee FBBO Gold Member FBBO Gold Member

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        FRIED points at the least! C'mon Crank, get back in the groove.Probably some bad wiring also.
         
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        • Daves69

          Daves69 Well-Known Member

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          I'd trace the output from the ignition switch.
          With the ballast disconnected (and not jumped) the "start" side should have battery voltage only in the "start" position and nothing in "run". The "run" position should have battery voltage only in the "run" position and nothing in "start".
          The ballast doesn't "have" to be there for an engine to run if the "run" and "start" circuits have been jumped. The ballast reduces voltage put to the stock coil when in "run".
          How an "internal ballast" coil affects this I'm not really familiar with.

          upload_2020-10-4_19-57-35.png
          ............
           
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          • OKDart

            OKDart Well-Known Member

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            Running with the ballast resistor bypassed will eventually burn up the coil. Maybe try a different coil?
             
          • OKDart

            OKDart Well-Known Member

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            • Cornpatch MO

              Cornpatch MO Well-Known Member

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              I bought a 64 Plymouth with that same problem. I found that there were two light brown wires . One was power only when the ign switch was putting power to the starter, and the other was 12 volts all the time. The wrong one was hooked up to the ballast or coil. ................................MO
               
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              • MoparDanMan

                MoparDanMan FBBO Gold Member FBBO Gold Member

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                If you turn on the ignition do you have voltage at the coil?
                 
              • MoparDanMan

                MoparDanMan FBBO Gold Member FBBO Gold Member

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                Well the engine will run without the ballast it's there to drop the primary voltage to the distributer so the points last longer and don't burn up. I would turn the ignition on and check for 12 volts at the positive side of the coil (I suspect you wont have it) then trace the wires back to the ignition switch
                 
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                • Cranky

                  Cranky Banned Staff Member FBBO Gold Member

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                  How is a ballast resistor checked? Can you run battery voltage on one side and it will be less on the other side? I've checked 3 of them and none shows a voltage drop.....
                   
                • MoparDanMan

                  MoparDanMan FBBO Gold Member FBBO Gold Member

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                  The ballast resister when cold will show battery voltage. When it heats up and then the voltage will drop. It should drop to between 6 and 9 volts
                   
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                  • MoparDanMan

                    MoparDanMan FBBO Gold Member FBBO Gold Member

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                    Take an ohm meter or a multimeter set to ohms, you should get 1.8 to 5 ohms of resistance.
                     
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                    • Cranky

                      Cranky Banned Staff Member FBBO Gold Member

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                      So if I leave it hooked up to my voltage tester, the volts will slowly drop?
                       
                    • hunt2elk

                      hunt2elk FBBO Gold Member FBBO Gold Member

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                      Probably will be a lower value than that even. I believe .7 - .8 ohm is a popular .
                       
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                      • dadsbee

                        dadsbee FBBO Gold Member FBBO Gold Member

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                        0.5 is OE..
                         
                      • Cranky

                        Cranky Banned Staff Member FBBO Gold Member

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                        I guess I need a digital VOM to see exactly what's going on since my 55 year old analog VOM isn't showing much but it does show a difference lol
                         
                      • oldbee

                        oldbee FBBO Gold Member FBBO Gold Member

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                        Lol, Crank don't worry about it! You're just getting older. Happens to all of us.
                         
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