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  1. #1

    Default 1985 Mustang GT Tach Not Working After MSD Distributor Install

    I unplugged the two connectors to the Duraspark box and removed it completely from the car. I also unplugged the factory connection from the factory distributor and removed it. I installed an MSD ready to run distributor part number 85031, the E-Curve dizzy and I can not get the factory tach working again. I left the factory 12V switched wire to the positive side of the coil. I connected the red wire from the MSD distributor to the positive side of the coil. I connected the orange wire from the MSD distributor to the negative side of the coil. Lastly I connected the black wire from the distributor to ground. The car starts and runs/drives with no issues other than the factory tach is not working. I have tried connecting the Green/Yellow wire that was previously on the negative side of the coil back to the negative side of the coil with no effect. I have tried connecting that same green/yellow wire to the green tach wire from the distributor with no effect. Now at this point I know what your gonna say. I need the MSD tach Adaptor part number 8920. I called Holley and they said that part is only for use with an MSD ignition control box which I do NOT have. Well, I bought one and installed it anyway to see if it would work and it did not solve my issue. I tried installing with using both methods as described in the directions, connecting the green wire from the dizzy to the white wire on the tach adapter and connecting the violet wire to the green/yellow wire that used to be on the negative side of the coil (without it being connected to the negative side of the coil) and I also tried green wire from dizzy to white on the tach adaptor and used the red wire connected to the green/yellow wire coming out of the harness (without it being connected to negative side of the coil) This also did not get the tach working.

    I even tried putting the duraspark box back in and connecting the two connectors but that did not help. I know I am missing something basic as I am by no means an expert. Please let me know what I am doing wrong if you can! I have called Holley a couple of times and they are awesome with customer service as usual but could not help resolve my issue.

    https://www.holley.com/products/igni...rs/parts/85031
    https://documents.holley.com/frm3010...85031_0319.pdf

  2. #2

    Default

    Green wire on the dizzy goes to the tach input as per the drawing on page 7 of the install manual you have linked.
    http://vb.foureyedpride.com/attachme...1&d=1418488062
    '83 351W TKO'd T-Bird on the bottle

    http://vb.foureyedpride.com/attachme...2&d=1418488063
    '93 331W Mustang coupe that beat your mom's LTD

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