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Need help on Briggs & Stratton 6.75 HP OHV engine electric diagram

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2025/06/27 11:01:17 (permalink)
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Need help on Briggs & Stratton 6.75 HP OHV engine electric diagram

Hi, I am wondering if anyone have, electric circuit diagram for Briggs & Stratton 6.75 HP OHV engine, I couldn't find anywhere I looked. This on a generator. I have no spark coming at spark plug, replaced the spark plug, on-off rocker switch and ignition coil, still no spark. I like to verify the ignition wiring circuit, of 6.75 HP OHV. If anyone can share any info on how wiring should be connected to rocker switch to the sensor connection to coil, like to know that too. Thanks in advance for the help! - CN
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    SRTsFZ6
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    Re: Need help on Briggs & Stratton 6.75 HP OHV engine electric diagram 2025/06/27 11:18:46 (permalink)
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    As we don't know the Briggs full model #, that would help tremendously..  
     
    IF it has a low oil cut off switch, usually on the side of the block, near the sump cover,
    it would have a single, thin BLACK wire going to it. 
    The switch is not unusual to go bad OR if indeed the oil is low-it'll kill spark.
    If it's there, simply un-plug it disabling it... 
     
    To check the coil (and everything else), pull off the starter cover. 
    Again, they'll be another thin black wire (not the same wire posted above)
    going to the coil, (often the back side of it).  That IS THE KILL SPARK WIRE
    when grounded. 
     
    Un-plug from the coil. Spin the engine over(cover back on), if you have spark, 
    the coil is fine. 
     
    If NO SPARK, either the coil is bad, or much less likely, a bad ground between the coil and block.
     
    Advise...
     
     
    .
     

    Scott
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    Re: Need help on Briggs & Stratton 6.75 HP OHV engine electric diagram 2025/06/28 15:36:41 (permalink)
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    Hi Scott,
     
    Thank you for your reply and advice,  I will follow the steps you advised again, below are details of the engine.
     
    Brigg & Stratton
    Model Number - 120312  0145   E1
    Link to parts catalog

     
    This is on an old Troy-Bilt 3550 Generator
     
    Thank you,
    CN
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    SRTsFZ6
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    Re: Need help on Briggs & Stratton 6.75 HP OHV engine electric diagram 2025/06/28 18:50:10 (permalink)
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    I'm not seeing a low oil switch on that engine:
    https://www.jackssmallengines.com/jacks-parts-lookup/manufacturer/briggs-stratton/briggs-stratton-engine/100000-19z999-series/120300-to-120399/120312-0145-e1 
     
     
    The generators are what usually have the low oil switches, especially the larger ones..
     
    Again, disconnecting the KILL wire should give you spark back..
     
    .
    post edited by SRTsFZ6 - 2025/06/28 18:53:53

    Scott
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    Re: Need help on Briggs & Stratton 6.75 HP OHV engine electric diagram 2025/07/01 14:16:41 (permalink)
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    Hi Scott,
     
    I followed the steps you advised again, disconnecting the KILL wire, still no spark. I tried with new and old coils, spark plugs, Rocker switches, still no spark. Part I didn't replace were the rectifier! (in Aluminum casing) in the middle of white wire (it is in the attached pictures). This engine does have the low oil sensor as you mentioned (Oil was changed recently and up max mark).
     
    I am suspecting wiring around magnet on flywheel may be the cause! not in the parts listed, looks like may have to replace the flywheel (Expensive $170...)

     I will try testing all again as suggested earlier! I will try to post photo’s separately, not allowing me.

    Thank you,
    CN
    post edited by [email protected] - 2025/07/01 15:24:33
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    Re: Need help on Briggs & Stratton 6.75 HP OHV engine electric diagram 2025/07/01 15:26:15 (permalink)
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    Not loading images (small) below 125 kb!
    post edited by [email protected] - 2025/07/01 15:36:59
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    SRTsFZ6
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    Re: Need help on Briggs & Stratton 6.75 HP OHV engine electric diagram 2025/07/01 17:54:08 (permalink)
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    The ignition coil doesn't need "any assistance" from any other electrical parts 
    on the engine to produce spark.
     
    If the Kill wire is removed from the coil, coil has a good ground, flywheel magnets
    present (and still magnetic) it should spark (with a known good plug).  
     
    Try another spark plug, simply touch the spark plug wire and ground your hand to the 
    block, you'll know if you have spark.  
     
    The coil is either good or not.  Sometimes they fail when hot, BUT, when dead cold, 
    isolated from everything else. it should fire.  If it does not, the coil is bad...
     
    I know you tried old and new coils, but it sounds as if their both bad...
     
    Any wiring under the flywheel would be for charging a starting battery-
    It won't have anything to do with spark...
     
     
    .
     

    Scott
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    SRTsFZ6
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    Re: Need help on Briggs & Stratton 6.75 HP OHV engine electric diagram 2025/07/01 17:57:58 (permalink)
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    Open an acct (Free) with Postimage:  https://postimg.cc/files
     
    Upload then dopy and paste the "Hotlink for forums" and your full pic will post:
     
     

    Scott
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