Rrrrrrr, need help on this one.

Electrical and Ignition

  1. pearljam724

    pearljam724 Well-Known Member

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    I just bought my car a few weeks ago. Car was running fine. For no reasonable explanation the in-line 40 fuse started blowing. I put a new fuse in. Everything powered back up. I attempt to start the car. It cranks for long as I want, but will not fire. As soon as I attempt to shut ignition key off. The fuse blows. I blew 10 fuses until I discovered a points condenser attached to negative terminal of coil. But, this distributor has been converted to electronic. I ran out of fuses before I removed the condenser thinking it shouldn’t be on there. Regardless, the car wasn’t blowing fuses prior to last couple days. I have same exact set up on a B body car and there is no condensor. So, I removed it. I’m usually pretty good at diagnosing problems. But, I’m going to need help on this one. I have no clue, why the fuse continues to blow now when I only attempt to start the car ?
     
    Last edited: Jul 10, 2020
  2. Dana67Dart

    Dana67Dart Like a fine wine, only getting better with age! FABO Gold Member

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    "condenser" is a noise suppressor, probably not the issue.


    We need a lot of info to help you.
    What year?
    What engine?
    What modifications?
    Why is there a 40 amp in line fuse?
    Where does the fuse go?
    What have you done to diagnose it?
     
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    • RustyRatRod

      RustyRatRod Bla de blizhibliz de blatde blizi bla bla FABO Gold Member

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      So I guess we're just supposed to know make and model, engine, "what the hell" circuit you're talking about. "and all that"
       
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      • kursplat

        kursplat FABO Gold Member FABO Gold Member

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        Rrrrrrr, need help on this one...we all will without the wiring diagram and a host of other items
         
      • 318willrun

        318willrun Utube channel 318willrun

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        Sounds like the long blue wire is crossed with the short yellow wire. Make sure they are not touching.
         
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        • pearljam724

          pearljam724 Well-Known Member

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          73 / 318 engine. Bone stock. The previous owner installed an inline 30 amp fuse where the fusible link typically goes. I noticed the car would lose all power at times. When it did, if I removed the fuse and reinstalled it. The car would power back up. But, it got to the point it would blow immediately. I replaced the inline fuse with a slightly heavier gauge one and installed a 40 amp fuse. It powers up every time. But, blows when I attempt to turn ignition key off when attempting to start it. I haven’t done anything to diagnose it. Because I don’t know where to start looking. I looked under the hood at most wiring and nothing appears to be a problem ?
           
          Last edited: Jul 10, 2020
        • pearljam724

          pearljam724 Well-Known Member

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          Which wires are these and where are they located ?
           
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          • 318willrun

            318willrun Utube channel 318willrun

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            Exactly. LOL... helps to be descriptive. I was throwing out a pun at you for the lack of info we had to go on in your first post. :)

            :thumbsup:
             
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            • 67Dart273

              67Dart273 FABO Gold Member FABO Gold Member

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              The condenser on the coil should be connected to POSITIVE side of coil. It is there to supress radio noise. I would indeed remove it until you find this cause.

              40a is likely not large enough. You have any idea how large your alternator is? Output current that is?

              I have few ideas. This is weird.

              So it still does not start? You have a test light? Some alligator clip lead "test leads?" How about a multimeter. We can make a few checks
               
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              • pearljam724

                pearljam724 Well-Known Member

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                I have most necessary tools. Multimeter, etc. The alternator is probably 60 amp. Most are. No mistake, condensor was attached to negative side of coil. Previous owner replaced coil not long ago and I believe he hooked the condenser up incorrectly. Based on he didn’t know how to fix basic stuff. Kickdown linkage, 2 barrel carburetor choke adjustment, etc.
                But, the car ran fine. As far as starting it and it idling, etc.
                 
              • Dana67Dart

                Dana67Dart Like a fine wine, only getting better with age! FABO Gold Member

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                What does your ammeter do right before the fuse blows.

                In 67 the fusable link goes from the starter thru the firewall to the ammeter then to the battery charging cir of the alternator and to the ignition switch and to the headlight switch.

                A short anywhere in those cirs would blow a fuse, but 40 amp dead short is hard on 18 gauge wires so I would expect you will find wires melted together.
                 
              • kursplat

                kursplat FABO Gold Member FABO Gold Member

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                especially x10
                 
              • j par

                j par Well-hung Member

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                Post some pictures and point at stuff they're worth a thousand words...
                 
              • pearljam724

                pearljam724 Well-Known Member

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                No wires are melted together. The inline fuse runs from the ignition relay attached on side of inner fender, by the battery. To the bulkhead middle connector. I didn’t take notice of what the ammeter does. When I get more fuses, I will check.
                 
              • 67Dart273

                67Dart273 FABO Gold Member FABO Gold Member

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                Here is one thing you could try. You claim that if you operate the starter then shut off the key, the fuse blows. Try this. Obtain a large wattage bulb. Like an old headlight or a stop/ tail lamp (1157, etc) Disconnect battery ground and hook the lamp in series. You will not be able to operate the starter. But mimic it. Twist the key to "start". This should cause the test bulb to light brightly. Let off the key to "run." Light should drop down to "not so bright." Now shut off key. Lamp should go clear out. If it does not, and or gets bright, you have a short. Now you can look around and find it. Try disconnecting the alternator, removing fuses, etc
                 
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                • 67Dart273

                  67Dart273 FABO Gold Member FABO Gold Member

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                  You cannot know that. Sometimes wires melt/ weld inside the harness wrapping
                   
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                  • harrisonm

                    harrisonm Well-Known Member

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                    Why not replace the fuse with an original/correct fusible link?
                     
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                    • kursplat

                      kursplat FABO Gold Member FABO Gold Member

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                      please, for the love of all that is electrical, don't just keep popping fuses in it. you need to crawl under there and start diagnosing this first
                       
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                      • Dana67Dart

                        Dana67Dart Like a fine wine, only getting better with age! FABO Gold Member

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                        For testing purposes I would get a low amperage fuse like 5 amps. Do not try starting the car but it will give you enough current flow to trouble shoot.

                        Also a fusable link is more like a slow blow fuse, so it is possible that the 30 or 40 amp fuse is just blowing too fast.

                        All that being said you need to get your cars wiring diagram so you can start tracing out your wires
                         
                      • pearljam724

                        pearljam724 Well-Known Member

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                        I ll post a little video, tomorrow night. Some pictures too.
                        I thought of that too. But, if it consistently blows 40 amp blade fuses. I would think that it would blow a fusible link too ? I think what i’m going to try to do is. Try to mimic the wiring connections on this 73 Dart to my 69 Coronet. They are nearly identical. I’m hoping this will help me pinpoint a problem. A wire has to be incorrectly grounding or touching somewhere, but I can’t see any issues. I’d rather rip a motor completely apart and put it back together than hunting for shit like this. It has to be related to ignition. No problems with accessories, lighting, etc. until the key is returned to off position. It will crank all day, if I want it to. Blows when I turn key off.
                         
                      • j par

                        j par Well-hung Member

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                        First try not to make wiring into a big thing. it's much much easier than rebuilding a motor and anybody can do the wiring at their own house not have to send things out to an expensive machine shop because we don't have tooling...
                        Simply follow the wire all the way back from where the fuses blowing to where the next connection is... I'm already suspicious if someone added a fuse to this from what I gather to something that already had a fusible link. Probably melting and burning out the fusible link and making a mess... Try not to throw another Band-Aid on it like the previous owner...
                         
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                        • pearljam724

                          pearljam724 Well-Known Member

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                          I understand, people add in line fuses because fusible links aren’t as easy to find and they tend to be a little more expensive. Plus, it’s easier to replace a fuse than it is a complete fusible link wire. Regardless, I don’t believe the inline fuse is the problem compared to using a fusible link. Something isnt wired correctly or a wire is touching something it shouldn’t be. It has to be on the ignition circuit.
                           
                        • j par

                          j par Well-hung Member

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                          Yes it's just straight down that wire the keeps blowing the fuse. When you get to the spot it will be fixed...
                          I haven't found fusible links hard to find there right next to the fuses at the parts store...
                           
                        • ragtopfury

                          ragtopfury Well-Known Member

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                          "I attempt to start the car. It cranks for long as I want, but will not fire"

                          Are you cranking so long that you're overheating the starter and blowing the fuse? Or does it do it if you only crank it for just 1 second as well?

                          If the 1st question is yes - ballast resistor? Ignition control box? Pickup in the dizzy? No fuel?

                          If the second question is yes, eliminate the ignition switch. Disconnect the ignition switch and crank it by jumping the starter relay - see if it blows the fuse from there when you let go. This may be a good place to start (no pun intended)
                           
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                          • pearljam724

                            pearljam724 Well-Known Member

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                            No, I can crank it for 2 seconds or 5-6 seconds and it still blows once I turn key off. I’m not over heating starter.
                             
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