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  1. #1
    Join Date
    May 2017
    Location
    Richardson, TX
    Posts
    115

    Default Electric Choke Connection - Sanity Check

    I have OMC equipped 574APERGD GM engine powering my King Cobra Sterndrive. The Engine is a crate engine and not original. Has Marine carb Holley 650 Electric Choke, Vacuum Secondaries. I removed it to install a kit. I noticed that the Purple/White Wire was connected to the EX terminal on the alternator. This conflicts with the OMC Service Manual which shows the Purple/ White wire for the choke connected to the AC Tap on Alternator.

    1) Is the Manual correct? (I realize that sounds like a really dumb question). If so, then I wired it incorrectly a couple years ago while trouble shooting another problem. I took the alternator off to get it tested and reinstalled.

    2) If the wiring has been incorrect all this time, could that explain chronically rich running carb?

    See pics of the choke wiring as it has been running and the pics from the OMC Manual. I attached the wiring and legend from manual.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    1992 Galaxie 20.5', OMC King Cobra 5.74LE,

  2. #2
    Join Date
    Apr 2009
    Location
    Long Island, NY,
    Posts
    184

    Default Re: Electric Choke Connection - Sanity Check

    Ok I recall trying to figure this out when I tried a Holley carb on my 4.3 but by then I switched to an Arco alternator with slightly different terminals. What you want to do is find a terminal that is at zero volts with the engine off but ignition on, and at charging sys voltage with the engine running. The choke should open fully in 3-5 min of run time. I think with the AC tap the output was both AC and DC volts.

  3. #3
    Join Date
    May 2017
    Location
    Richardson, TX
    Posts
    115

    Default Re: Electric Choke Connection - Sanity Check

    Thank you sir,
    I'll get my multi-meter an check it out.
    1992 Galaxie 20.5', OMC King Cobra 5.74LE,

  4. #4
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    11,996

    Default Re: Electric Choke Connection - Sanity Check

    FYI and FWIW......
    We will see two methods for supplying power to the 12 vdc helix heating element, of which opens the normally closed choke chimney.

    ..... power when the ignition key is ON... engine running or not.
    If the engine does not start immediately, the choke chimney begins and continues to open.

    ..... alternator derived power only when the engine is running.
    If the engine does not start immediately, the choke chimney remains closed.


    I prefer using the alternator circuit for this.


    BTW, since by default the choke chimney is closed on a cold engine, these should be called an "Electric Un-Choke" system.





    .
    Last edited by RicardoMarine; 04-25-2020 at 09:17 AM.
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP drives

    "Intellectual growth should commence at birth and cease only at death." Albert Einstein

    Please... no PMs! Post your questions on the forum.

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