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Hot!Backfiring, running rough, smoking, etc

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jcw
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2017/08/01 00:15:42 (permalink)
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Backfiring, running rough, smoking, etc

My JD LA130 with Briggs and Stratton has been great until yesterday. It has 280 hours and well maintained. 2 weeks ago my teenage son did not turn key all the way off and drained battery. Quick charge and it started and mowed yard which took 25 minutes. Yesterday I tried to start it and turned over, started and then died. Battery did not turn it over again. I charged for 10 minutes or so and tried to start but wouldn't. I had little time so I switched to 50 amp and started it. Immediately it ran rough, smoked, and would not idle. I fully charged battery and tried again. Started and stayed running but was very rough, backfired, and smoked. I pulled plugs and they were very dirty.

After work today I charged battery again (which did not need much), cleaned air filter, put in new spark plugs, and started again. It was little rough so I sprayed some carb cleaner in it and it was still a little rough but was much better than day before. No smoke. After letting it warm up I increased rpms and it seemed to be running well. Wasn't perfect but good. I tried to drive it and immediately almost died. I stopped and it was smoking some and was very rough again. It would also backfire some. I turned it off and plugs are very dirty.

Did I burn up the coils? Any suggestions?

I would appreciate any help!

12 Replies Related Threads

    Wilber
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    Re: Backfiring, running rough, smoking, etc 2017/08/01 08:19:55 (permalink)
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    Sounds like a timing issue, probably caused by teenageritis.
    Mikel1
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    Re: Backfiring, running rough, smoking, etc 2017/08/02 18:29:30 (permalink)
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    What color smoke and are spark plugs dirty from oil or fuel? How is the oil level? Any fuel in the oil?
    jcw
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    Re: Backfiring, running rough, smoking, etc 2017/08/02 20:40:00 (permalink)
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    Blackish smoke. Spark plugs look like dirty from oil. Oil level is fine but just started running poorly. No fuel in oil. Thanks for the help
    Mikel1
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    Re: Backfiring, running rough, smoking, etc 2017/08/02 23:06:04 (permalink)
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    Black smoke is from burning too rich.
    Are both cylinders working?
    jcw
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    Re: Backfiring, running rough, smoking, etc 2017/08/03 08:22:30 (permalink)
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    Both cylinders are working. Both turned brand new spark plugs black with less than 5 minutes of running
    Mikel1
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    Re: Backfiring, running rough, smoking, etc 2017/08/03 08:44:21 (permalink)
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    Not much affects both cylinders at same time. Too much fuel will wash cylinders out which washes off carbon, this makes spark plug black and wet. Excessive crankcase pressure can cause oil to foul spark plugs. Is oil coming thru oil breather hose?
    jcw
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    Re: Backfiring, running rough, smoking, etc 2017/08/07 10:30:48 (permalink)
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    I replaced both ignition coils and it runs great.
    Roy
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    Re: Backfiring, running rough, smoking, etc 2017/08/07 11:25:50 (permalink)
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    It seems odd both coils would fail at the same time. I would have suspected the wiring harness, it has two diodes that prevent the armatures from firing simultaneously. If one pops, one cylinder will fire out of time. They can be replaced individually but it is a lot easier to just change the harness.
    jcw
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    Re: Backfiring, running rough, smoking, etc 2017/08/07 21:12:49 (permalink)
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    Hi, thanks for all the input. Even after knowing better but being in a hurry and frustrated, I used the 50 amp starter function on my charger and must have fried them. $80 mist
    jcw
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    Re: Backfiring, running rough, smoking, etc 2017/08/07 21:13:02 (permalink)
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    Mistake
    AVB
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    Re: Backfiring, running rough, smoking, etc 2017/08/07 22:08:40 (permalink)
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    That should not damage them either. These coil are isolated from the electrical system other grounding to kill the output. They are triggered magnetically and their output voltage is also developed magnetically. I seen on system that didn't have the steering diodes to be damage from 12v being applied the the kill terminals but in this case the diodes would prevent such voltage application. So I am also curious as why they both failed at the same time. Very unusual.
    Mikel1
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    Re: Backfiring, running rough, smoking, etc 2017/08/15 14:03:35 (permalink)
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    Doesn't make much sense, I guess I was assuming the pull the plug on one cylinder then the other cylinder test was done.
    Anyhow glad you got it working now.
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