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Can't get fire to plugs

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  • LoganpClayton
    replied
    Dle,

    Logan here, Firstly, make sure you read the good info supplied by duaneb55


    Originally posted by duaneb55 View Post
    Because the oil pressure switch is open with the engine not running, there will not be any 12VDC at the coil with the ignition switch in the RUN position. However, there should be while cranking as the by-pass diode allows 12VDC(+) to the coil from the START signal at the starter.

    If you have 12VDC(+) at the coil while cranking and still no spark at the plugs then I suspect the ignition module behind the flywheel has failed.

    PM me an email address and I'll send you the engine Service Manual that covers testing.

    Now that you have made 100% sure you read it, any questions?

    One note that I would make is that the easy way to do this with no tools and little electrical background is literally take the plug out, lay plug on it's side, on something metal, and see if you get any arcing across the gap. I say this is the easy way but in reality it can be quite tricky. The real "easy" way is to have tools to help you do the job, one that I use as a go-to for no start issues is a spark gap tester, as seen below: Click image for larger version

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    This baby takes the spark plug wire right to it, then you clip the alligator onto the top of your existing plug, you should see spark (if not something is wrong with coil/supply) *these tools are a whopping 4$ on ebay*


    To start an engine, as we all probably know, you need Fuel, Air, Spark, and compression. If you have checked off Compression, Fuel, and if there is no obvious blockage stuck in you're intake for air, then it comes down to spark. Here is a detailed diagram for the B48M Onan Engine used on the AEAD welders:
    Click image for larger version

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    One thing I will note is that the coil pack under the flywheel seems to only be used for the charging system. now, back to the beef and taters:

    If you have Voltage at the ignition coil, and it's grounding that primary of the ignition coil properly from the breaker & cap assembly, then either that coil has a bad secondary, or there is an issue from the secondary on (spark plug wires, or plugs them-self).


    Let me know how it goes!
    Last edited by LoganpClayton; 02-01-2017, 04:17 PM.

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  • dle
    replied
    not yet, I was told to check the CB4, self set breaker???

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  • D Auger
    replied
    Any luck yet ?

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  • dle
    replied
    My model number is 903039

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  • duaneb55
    replied
    I couldn't find where the John-Deere manual covered troubleshooting the ignition module. Just changing it.

    The Onan manual I emailed has the troubleshooting steps as well. If you want one too, PM an address.

    Leave a comment:


  • H80N
    replied
    This one...???

    http://www.mytractorforum.com/images...6_18_20_24.pdf

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  • duaneb55
    replied
    Because the oil pressure switch is open with the engine not running, there will not be any 12VDC at the coil with the ignition switch in the RUN position. However, there should be while cranking as the by-pass diode allows 12VDC(+) to the coil from the START signal at the starter.

    If you have 12VDC(+) at the coil while cranking and still no spark at the plugs then I suspect the ignition module behind the flywheel has failed.

    PM me an email address and I'll send you the engine Service Manual that covers testing.

    Leave a comment:


  • D Auger
    replied
    Post some pics of the machine please and the engine id tag

    Leave a comment:


  • H80N
    replied
    Originally posted by dle View Post
    model JK641540
    that looks like a serial number

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  • dle
    replied
    model JK641540

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  • dle
    replied
    Its the Onan, can it be a failed CB4 switch?

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  • D Auger
    replied
    Any luck yet ?

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  • H80N
    replied
    Which engine do you have....?? Onan or Kohler...??? Model...??

    sounds like you could use an engine manual
    Last edited by H80N; 01-13-2017, 05:12 PM.

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  • D Auger
    replied
    Sorry on last post check for 12volts at coil+

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  • D Auger
    replied
    With switch in run position ignition on you should have 12 volts at coil if not check your ignition switch for 12 volts coming out the switch when switched to run make sure your battery is fully charged ,any pics of the machine ?D

    Leave a comment:

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