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Electrical and Ignition

  1. Shane

    Shane Well-Known Member

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    well in the rain with no hood and roof I took out my newly installed 340, in my 68 barracuda..(i couldnt help myself)
    IT WAS FANTASTIC, as it was the first time i have driven a 340... But the shitty started right before I pulled in my garage....i was concerned about this and clearly for a good reason as it turned into a problem..

    the car made a noise and died out...white smoke came out of the hood...i have a brand new year one wiring harness and the main red power wire line that goes into the firewall's fuse BLEW....

    The reason I was concerned about this was that a local alternator shop re-did my alternator to 70-75 amps.....

    what, from all your guys experience is the best way to solve this issue so I can run the car with no problems?

    I would like to keep the factory amp meter, but if it has to go, it has to go...would replacing the line fuse with a larger line fuse take care of the problem???

    Thanks again

    Shane
     
  2. 63dartman

    63dartman Well-Known Member

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    First thing to do is find out why the fuse blew. What size fuse is it? If it's a primary wire I would think it's fairly large and to make the fuse blow it had quite a bit of current passing through it. Are you sure you don't have anything shorting to ground that caused it to blow? I wouldn't jump to conclusions about the alternator right off the bat. Good luck.
     
  3. Shane

    Shane Well-Known Member

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    well that is a good point....this is my first car I have ever done so... I have a good ground from the battery to the block, and from the battery to the front of the car(where the rad bolts into)

    What I didnt do in my excitment was ground the motor to the firewall....

    could that have caused it?


    Shane
     
  4. hemiduster

    hemiduster Well-Known Member

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    I agree with 63 about jumping to conclusions but in the end it wouldn't surprise me that the factory amp meter is the culprit. Good luck!!
     
  5. Shane

    Shane Well-Known Member

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    i also agree to not jump to conclusions....But a collection of all the opinions of everyone one on here will help...
     
  6. 68gts340

    68gts340 Well-Known Member

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    the firewall ground is needed , but most likely not the problem , sounds like a dead short.( amp gauge ?)
     
  7. Shane

    Shane Well-Known Member

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    by dead short you mean the wires may be touching on the back of the amp gage under the dash?

    Everywhere else looks to be ok... I'll check that gage when I get home tonight...

    I have some new fusable link I will put in tonight...
     
  8. RedFish

    RedFish Well-Known Member

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    The amp rating is what the altenater is capable of not what it puts out constantly. a dead short is hot contacting directly to ground which should and will blow any amp fuse you try. A fuse is a safety devise to protect a circuit. If it dont burn something else will.
    Find the short which is probably a wire overheated and melted to something (my best guess) since you did drive it a while.
     
  9. JR

    JR Pissed off senior member.

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    What size is/was the main alt. wire? Any time you run an alt. that is more than 65 amps you need to beef up the main wire. I had a 77 monaco that I ran a cop alt on and it fried the stock wires I upgraded them to bigger wires and it solved the problem.
     
  10. OneOfMany

    OneOfMany Well-Known Member

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    After re-reading the original post, you say the smoke coming from under the hood, and the red wire. I think maybe when you say "firewall fuse" you're referring to the bulkhead connector where all the wires pass into the interior. If so, then this is common if you are drawing more amps through the ammeter. There are many here that can provide the link to run the (heavier) main wire through a different location on the firewall.
     
  11. Shane

    Shane Well-Known Member

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    Yea thats what I was trying to mumble out in the original post....I have the link saved that shows how to by pass the ammeter....Is that what I should do, or would a Heavier gage wire ran to the meter work?
     
  12. 68gts340

    68gts340 Well-Known Member

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    if you have an electric multi meter ,,, you can use it to check for a dead short...go to the wire that burned, find where it goes to and check it at that point for continuity to ground...if it shows open circuit it is not shorted...if it does show continuity to ground you have a dead short somewhere... check it key off.. every thing off.. even the dome light
    .hope this helps you..
     
  13. Shane

    Shane Well-Known Member

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    well i found the problem...it was in the amp meter...Do I have to re-do the fuseable link, or can i jsut put a line with a new style fuse in, so if it blows again its alot easier to fix?
     
  14. RedFish

    RedFish Well-Known Member

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    The high amp heavy duty type fuses found under the hood of later models would work but the little blade type used in interior fuse panels will not.
     
  15. ted_sweet

    ted_sweet Well-Known Member

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    any good parts store has fusible links.
     
  16. dgc333

    dgc333 Well-Known Member

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    I can't see how the Amp gauge would cause the smoke under the hood and a fuse to blow. The amp gauge is nothing more than an in line shunt with a small meter across it that senses a voltage drop across the shunt.

    The amp gauge can fail by the meter going bad but the electrical system will still work. Or the shunt could over heat due to to much current and fail open in which case its the same as opening a switch or a fuse blowing.

    What you describe is an indication of to much current flowing through the circuit due to a short to ground, or a high resistance connection in the bulked connector or possibly to much output from the alternator because of a bad regulator or simply a low battery causing the alternator to output its full capacity exceeding the wires rating.
     
  17. MVRCorp

    MVRCorp Well-Known Member

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    I actually drilled out the fusable link terminals on the connector block and ran a 10 ga wire thru the firewall to the underside of the dash. I'm now using a 50 amp slo-blow fuse in it's place. The only problem I had is I tied my main amp feed ( it has a 25 amp fuse in line) to the amp meter side of the 50 amp fuse and blew the 50 amp fuse. I have since tied it in prior to the 50 amp fuse and have had no more problems.
    I alway keep a spare 50 amp fuse in the glove box.
     
  18. NiceFishEh

    NiceFishEh Well-Known Member

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    Shane:

    I did the amp bypass on mine when I had the dash out with good results.

    Some guys take the two wires off the amp meter and bolt them together. It's a short cut to what MAD says, but will work if you bulkhead is in good shape. In most cases it's not. I would replace the fusible links for what they are worth.
     
  19. Shane

    Shane Well-Known Member

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    thanks everyone for the ideas....I have tried many different things, and it did it again tonight....Its frustrating that i have made it this far with this car and it actually starts and runs, and yet just when it seems liek all is good...it smokes and wrecks alot of wires....

    I was coming on here to ask if anyone has a picture of their starter relay I can see...(just want to see it to clear something up in my head)

    But DGS333 your reply has me thinking... they only thing I havent really ruled out in my head so far is the regulater...perhaps I screwed something up there.....is there two wires off the new year one harness that go to the regulator?
     
  20. Shane

    Shane Well-Known Member

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    OK....dgc333's point has really rung a bell for me...When i first got the car, its wiring was modified to run an electronic set up...with a dual ballast resistor (at the time i did not know this, and went ahead and ordered a new year one harness for a a points set up with a single ballast resistor)
    the problems started when I changed the motor and once it was in, i put in the new wiring harness i ordered...

    I have spent the last week trying to make the car run for longer then 20 minutes without smoking and blowingmy fusable links and yesterday my msd box....i got lucky and got a new one under warranty...

    can you explain to me how to properly wire up a points, single ballast resistor wiring harness to run with an electronic distributor and msd 6al ignition...... this has to be my mistake as I have elminated almost everything else....

    what info i could really use is , I can bypass the ballast resistor because of the msd, correct?

    then which wires from the new harness do I use to run to the voltage regulator ?


    as dgc333 mentioned, it may be a bad regulator....or perhaps i dont have my wired properly and the car is running without one.....which is leading to my problems...

    THANKS AGAIN

    Shane
     
  21. cuda65vpt

    cuda65vpt cuda65vpt

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    this may be a dumb suggestion, but you did check for a wire that could be touching the exhaust and only shorts out when hot.
     
  22. fstfish66

    fstfish66 Well-Known Member

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    when using points,the ballist resistor is in line,,when you use a MSD box,you eliminate the ballist resistor. the MSD requires 12 volts constantly, when using points the ballist cuts the voltage to 6 volts i belive when the car starts,,

    a i am pretty sure the MSD has nothing to do with you blowing the fuseable link,, you either have a short,,or a dirty/weak conection . what year is the car ?? what charging system ?? single or dual field altenator ? pre 70 voltage regulator ?? blue regulator from mopar ??

    sounds like a weak or dirt conection,
     
  23. pauly v.100

    pauly v.100 Well-Known Member

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    I put a reman 75 amp alt. in my car and had same problem. My alt. only needs 1 wire and the old one had 2 hooked up, something like that. I had to splice a wire at the regulator. Was awhile back so I'll go look in the morning and see how my setup is hooked up... get back to ya !
    -aloha
     
  24. dgc333

    dgc333 Well-Known Member

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    If you don't have one you need to get a multimeter before you try starting the car again and really burn something up. A digital multimeter sufficient to trouble shoot car electrical systems can be purchased for less than $20. The multimeter will have DC voltage settings for measuring the elctrical system and resistance settings to check for continuity and look for shorts.

    Since you have the engine running I would guess you have the MSD box hooked up correctly but to check; The purple and green wires hook up to the two pick up wires from the distributor. The small black (-) and orange (+) wires attach to the coil - and +. The large black wire needs to connect to a soild ground, I attached mine to the block near where the MSD box is mounted. The LArge red needs to attach to a constant 12 v battery source. I hooked mine to the same terminal on the starter relay as the 10 gauge wire from the (+) side of the battery. The small red wire needs to be connected to swiotched 12 volts. Now that is easier said than done on old mopars. Everything that is switched on with the key in the run position is off in the start (engine cranking) position except for the ignition and that position bypasses the ballast resistor. The best way to hook up the small red MSD wire is to hook it to the blue wire that would normally be connected to the (+) side of the coil. You don't need to bypass the ballast resistor but bypassing it elminates something that can fail. On my car I just took a piece of 18 gauge wire and put male spade connectors on the ends. Just plug it into the two connectors that would normally plug on to the ballast.

    A quick word about grounds. If you have bad grounds all kinds of gremlins will rear their ugly heads. You should have a solid 8 gauge or larger ground wire from the engine block to the firewall. I also have another ground wire from the (-) of the battery to the radiator core support. I also use toothed lock washers under the fasteners that attach the grounds to ensure I have bite into the base metal.

    I am assuming the alternator you had rebuilt was a pre 70 style alternator and you still have the pre 70 style voltage regulator. The regulator needs a good ground (remove the paint where the regulator contacts the car and use toothed lock washers. This style of system works by switching voltage to the field windings of the alternator. The newer style has two field connections with one being switched 12 volts and the regulator controls the path to ground.

    You trouble shoot the charging system with your multi meter on a DC voltage setting that will read to 20-30 volts. With the engine running and the volt meter across the battery terminals you should read 13.8-14.1 volts. Reving the engine to greater than 2000 rpm may make a momentary increase in voltage but it should come right back to the voltage at idle. And, turning on all your lights, wipers, heater blower, radio, etc can make a dip in the voltage but it should come back to the 13.8 to 14.1 volts by reving the engine to 2000. If it perfroms this way and you still have the fuse blowing issue after a few minutes then there is a short occuring some where. Real close examination of the wiring and using the multimeter on a resistance setting looking for a short will be required. If you haven't trouble shot short issues before you should enlist someone with some experience to help.

    If you get a high reading (15 +) when measuring the the voltage across the battery but it otherwise it acts as described above you have a bad connection somewhere that is casuing a voltage drop. Measure the voltage at the power terminal of the regulator is shouldn't be any more than 1/2 a voltage lower than the voltage across the battery, same with the voltage at the output terminal on the regulator. If it is larger than 1/2 volt then you have some bad connections. The output of the alternator goes through the bulked connector to the amp meter and from the amp meter back through the bulked connector to the starter relay to the battery. Makes sure all those connections are clean and tight. The regulator gets its power through the ignition switch, fuse panel and bulked connector any one of these connections can cause enough voltage drop to cause the regulator to over charge.

    If when measuring the voltage across the battery it varies directly with rpm and continues to rise with rpm then the regulator is not working. Check the regulator ground. Also, the regulators are cheap enough (around $10) at the local parts store its not much point messing with them.

    If you disconnect the the regulator from the alternator and it still outputs voltage (more than 12.8) then the alternator internally has an issue.

    NOTE: if the alternator is not a stock mopar type alternator then some of these instruction don't apply and I would need to know what it is to help.
     
  25. RedFish

    RedFish Well-Known Member

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    I'm throwing this in even though it may not be relevent.
    Friend of mines Chevy pickup problem. Smelled something burning and charging system fails along with most everything else. His local garage replaced altenater (built in regulater type), repaired burned slot in fuse panel under dash and on the road again.
    This all happened 3 times before he had a wrecker drop the truck here. Only clue he had to offer was "Never fails going to work and back. Only when I hook up the boat and head for the lake."
    This model chevy has a large red battery wire to the top of the distributer. That wire was out of its original loom and its casing had melted through, very small spot .
    Engine heat would cause the wire to move just enough to touch the intake. Dead short to cast iron ! Took about 2 hours for me to discover it and 5 minutes to fix it.
     
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