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    Author Topic: msd blowing fuses  (Read 2982 times)

    Offline Madmaxx

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    msd blowing fuses
    « on: August 24, 2014 - 11:04:34 PM »
    ok..lets start in the beginning..lol... put on a relay harness for my headlights  works great!..replaced my old alt which was barely keeping up with a 78 amp rebuilt..13.5 at idle 14.3 above 900 rpms ..ran 2#10 wires from alt to starter relay..unhooked lines from my amp gauge and bolted together wires and taped them up...all was good drove for about 1/2 hr with lights on awesome!!  pulled in shut car off opened garage door no start!!..blown msd fuse..15 amp just going to msd 6a..keeps blowing them..no start/spark?  my friend thinks the msd is dead (and I do too) just dumb luck here? we are thinking the msd lived a life of 12 or less volts  and now it was seeing 14?  ideas? comments?  thanks
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    Offline Chryco Psycho

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    Re: msd blowing fuses
    « Reply #1 on: August 25, 2014 - 06:52:03 AM »
    14 v is normal operating voltage , so it should not damage the MSD , if you replac the fuse will it start again ? If so the MSD is ok
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    Offline Madmaxx

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    Re: msd blowing fuses
    « Reply #2 on: August 25, 2014 - 07:35:55 AM »
    replacing the fuse, it does not blow until you crank the motor then after 10 sec. of cranking it blows the fuse..never attempts to fire..i'm pretty sure its dead...I've never been a fan of msd units for street..back in the day I had seen many friends get stranded by these units...it was already on the car when I bought it...I think I'm going to eliminate it for dependability reasons..just seems odd that it would happen right after I changed the alt. but I did check that and it was 14.4 was the max at the battery.. thanks CP
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    Offline Madmaxx

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    Re: msd blowing fuses
    « Reply #3 on: August 25, 2014 - 06:11:57 PM »
    ok as the world turns!..lol..it appears the coil is dead..so replaced the coil car starts...all good right..not so fast!!..the msd continues to blow a 15 amp fuse..if it starts right up all fine..if it has to crank a few revs blows the fuse....so for fun tried a 20 amp fuse..no prob..starts runs drives all good? maybe new coil is pulling a few more amps?  it was an old used coil I had laying around..known good one!... :clueless:
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    Offline Bullitt-

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    Re: msd blowing fuses
    « Reply #4 on: August 25, 2014 - 08:18:57 PM »
    no fuse mentioned in instructions for MSD6A http://www.msdignition.com/Products/Ignitions/Daily_Driver/6201_-_Digital_6A_Ignition_Control.aspx

    I see several forum post like this one suggesting msd says not to fuse http://www.chevelles.com/forums/showthread.php?t=322120
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    Wade  73 Rallye 340..'77 Millennium Falcon...13 R/T Classic   Huntsville, AL
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    Offline dodj

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    Re: msd blowing fuses
    « Reply #5 on: August 25, 2014 - 08:23:27 PM »
    I have no fuse in mine. This post made me think I better check to see if I should have a fuse.
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    Scott
    1973 Challenger  440 4 spd 
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    Offline Madmaxx

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    Re: msd blowing fuses
    « Reply #6 on: August 25, 2014 - 09:27:55 PM »
    I have never had them fused either but my mechanic is a racer that knows his stuff..he suggested it? what do you think would have happened without it?..my guess a completely dead msd box..which might have been a blessing lol..I do know he has talked to the msd tech many times and has had a few rebuilt by msd.. I'm personally not a fan.. thanks for the input!
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    Offline Chryco Psycho

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    Re: msd blowing fuses
    « Reply #7 on: August 25, 2014 - 11:49:15 PM »
    I am not a fan either & have seen a number of them fail stranding people miles from home . , nothing is perfect but a spare ballast & ecu is easy to carry or find at any local parts stores
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    Offline HP_Cuda

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    Re: msd blowing fuses
    « Reply #8 on: August 27, 2014 - 03:22:23 PM »

    Wild I wonder if this has anything to do with it? I didn't know this even went on...

    http://www.gotellispeedshop.com/Counterfeit_MSD_boxes.html
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    1970 Cuda Clone 440 4 speed - sublime green
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    Offline Madmaxx

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    Re: msd blowing fuses
    « Reply #9 on: August 27, 2014 - 09:26:31 PM »
    AWW now that's just plain scary!!..I looked and sure enough mines real..lol did some calculating..we figured out that 12.5 volts would be 14 amps but 14.5 volts would be 16 amps..just enough to blow the fuse at certain times..its been fine with the 20amp fuse..still going to delete the msd box..i'm just not comfy with it..and if something did happen it would be nice to have spare parts either in the trunk or at any box auto parts store. thanks for the replies!!
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    Offline brads70

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    Re: msd blowing fuses
    « Reply #10 on: August 27, 2014 - 09:44:37 PM »
    Quote from: HP_Cuda on August 27, 2014 - 03:22:23 PM
    Wild I wonder if this has anything to do with it? I didn't know this even went on...

    http://www.gotellispeedshop.com/Counterfeit_MSD_boxes.html


    That's nuts! :stomp:

    I've had MSD boxes for over 20 years and never had one go bad. A local short track racer was clearing out parts and I bought 2 of the black Mopar Performance MSD boxes, thinking one for a spare . It's been on my car for 5 years now with no issues. The 2 other cars I've had them on I ran them for 12 years each and they were daily drivers.   
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    Brad
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    Offline dodj

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    Re: msd blowing fuses
    « Reply #11 on: August 27, 2014 - 10:18:25 PM »
    Big fan of MSD here.
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    Scott
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    2007.5 3500 6.7 Cummins Diesel, Anarchy tuned.
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    Offline Madmaxx

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    Re: msd blowing fuses
    « Reply #12 on: August 27, 2014 - 10:38:04 PM »
    yes I do understand!! they have their pluses.. my mechanic loves them...I have seen the other side  lol..and maybe they weren't installed right etc...I'm just not willing to risk being stranded...I'm glad ur exp. has been good!!..if I was in a search for every last ounce of hp..maybe..lol..
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