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Ignition problem No spark

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DMcQ
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2020/09/18 18:53:40 (permalink)
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Ignition problem No spark

Hi all, I have a B&S Intek 24 HP engine on a Husqvarna YTH24V48 lawn tractor. I've been trying to get her running again for weeks. Thought I had a fuel problem so replaced the gas line, filter, fuel pump, carburetor, intakes and air filter. Then focused on the ignition. Coils tested bad so replaced those along with the spark plugs. I tested the seat cut off switch as well. Cleaned the magnet on the flywheel. However, I'm not getting spark from the plugs. So I pulled the cut off wires from the coils and figured I could manually ground the coil to shut it down but, still no spark. So....I'm at a total loss now. Don't understand how I'm not getting spark when the cut off wires are removed from brand new coils?? Any help would be appreciated!!
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    Roy
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    Re: Ignition problem No spark 2020/09/18 23:15:23 (permalink)
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    How are you testing for spark? Are you grounding the plugs on the engine block?
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    AVB
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    Re: Ignition problem No spark 2020/09/19 08:26:57 (permalink)
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    It is a good chance that a positive voltage has been applied to the ignition coils terminals as this destroys the electronics.  Reasoning here is that the fact both coils failed which is very unusual.
     
    Even a monetary pulse is enough to destroy the coils if the blocking diodes are shorted. With kill wire disconnected at both coils normally you will have spark even if the diodes are shorted. But when voltage is applied it destroys the electronics. Test the leads for while disconnected by cycling your ignition switch for voltage.
     
    BTW just throwing parts at an engine is no common sense way to repair it and it can get very expensive fast.
     
    Plus please post the model and type number of the Briggs engine. I know it is probably a 440000 series but need to know exactly for parts lookup.
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    DMcQ
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    Re: Ignition problem No spark 2020/09/19 09:12:15 (permalink)
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    Roy, yes, I pulled one plug and held it to the engine to provide a ground, then engaged the starter and looked for spark.
    AVB, That's concerning that the coils could have been destroyed that way. These are new coils that I just installed, so if that is the problem I have to wonder what I did wrong that allowed that to happen? I can't think of a way that power was applied to them aside from cranking the engine start and the flywheel magneto passing across them. BTW, I agree with you about "just throwing parts" at an engine, but in this case, with the hours I had on this engine I felt a new fuel pump was a good idea. The gas filter is expected but the gas line was dry rotted and bad. The carb was replaced mainly because I wanted new gaskets and they were hard to find solo however for $30 I could get gaskets and the carb...and I was trying to hurry up and get the mower fixed as the grass was getting out of hand. That didn't work out so well and bought a new John Deere zero turn. Trying to get the Husqvarna running again just to sell it. Anyway, the info on the engine is: B&S Intek 24 HP, Model 44R877, Type 0001G1, Code 140825YG. Again, any & all help is very much appreciated. Thanks Roy and AVB!!
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    AVB
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    Re: Ignition problem No spark 2020/09/19 10:31:12 (permalink)
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    It not something you did if the voltage did feedback. Ignition switches do develop carbon arcs. Not to common but it does happen. I one a couple years that was sending about 2 volts to the ignition coil it took out the originial coil amd the first replacement coil. Knowing that this cold happen I checked the kill line before putting on a second replacement coil and when I found the 2 volt pulse as I turned the ignition switch.
     
    You your setup that there should be two diodes in the kill wire harness. IF there should happen to short out this can allow the voltage to pass if Briggs installed them correctly. IF wire as the diagram indicates then nothing stops the voltage application. The Briggs wiring indicates the anodes are being  grounded which doesn't make any sense to me as electronics technician. To me it should be the cathodes that are grounded.
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    DMcQ
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    Re: Ignition problem No spark 2020/09/20 14:32:58 (permalink)
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    Thanks AVB, I tested the coils and believe they are bad (again) so you may be right. I'm going to check the cut off wires for the stray voltage. If there is a stray, I'm guessing I should replace the ignition switch and kill line harness? Seems like that should stop a stray voltage. Anyway, at least what you have proposed as the possible problem makes sense when nothing was making sense to me before. Thanks for your help!
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