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Hot!Spark present, still not starting - 5HP Tiller

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blaubner
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2020/03/29 18:57:21 (permalink)
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Spark present, still not starting - 5HP Tiller

Howdy,
 
Bought a used Craftsman front tine tiller with a 5HP Briggs & Stratton last spring. When I bought the machine it took a lot of pulls to start, but it would eventually start. I used it handful of times, ran the motor until the gas ran out, then put it in my shed for the winter.
 
I tried to start the engine this weekend, but I broke the pull cord after 5/6 pulls. When I opened the mechanism to re-install the cord, I noticed that the recoil spring was broken at the end. Instead of getting a new spring, I used some pliers to crimp the existing broken end of the spring, reinstalled the cord, and everything on seems to be pulling just fine now.
 
However, the engine will not start. When I remove the spark plug from the motor and pull the cord I see no spark. I replaced the existing spark plug with a new one. Same result; no spark. I removed the lead from the spark plug, then tested the coil with my multimeter. The coil is showing resistance when I test the from the lead wire and the cutoff switch (2.68 ohms when the multimeter was set to 20k). Seems like the coil is working properly. 
 
- Is it possible that I'm not getting enough RMPs from the flywheel because of my recoil spring mod? It seems to be spinning just fine right now
 
- I replaced the existing spark plug with the same exact one. However, the old spark plug has a much larger gap than the new spark plug. I read online that the gap should be 0.030 inches. The new one looks more like 0.030 than the old one. 
 
I'm new to small engines but enjoy the work. What should I test next? Happy to post any photos that would help.
post edited by blaubner - 2020/03/30 10:16:49

7 Replies Related Threads

    Mrcalm
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    Re: No Spark - 5HP Front Tine Tiller 2020/03/29 20:35:08 (permalink)
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    Hello; I for one have had little troubles like this before in small engines, like lawnmowers. What I suggest is taking off the flywheel cover and remove the coil. Take some fine sandpaper and sand the coil surfaces where it faces the flywheel. Then sand the magnets on the flywheel so that the surfaces are clean. Now only sand the magnets on the flywheel, the rest of the flywheel won't need it. Replace the coil and gap the coil to the flywheel with a matchbook cover to gap the coil to the flywheel. Put it back together and if it isn't flooded to bad my experience is it will start and start easier than it has. Now also make sure the fuel system is working properly as well. Hope this works. Good luck.
    AVB
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    Re: No Spark - 5HP Front Tine Tiller 2020/03/29 21:35:28 (permalink)
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    Rust does not affect the magnetism. Also it is impossible to test Magnetron ignition coil. So you don't need to sand the flywheel or the coils legs that faces the flywheel. Totally unnecessary unless the rust is interfering with the flywheel rotation. Either the coil works or not. It does however affect the grounding of the coil to the cylinder. Normal air gap is .010" which most business cards are.
     
    Make sure ground the plug the metal cylinder head when checking for spark.
     
    Depending if it is a L-head or not . If so the valve clearance may have close to the point where there is severe lost compression.
    blaubner
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    Re: No Spark - 5HP Front Tine Tiller 2020/03/30 08:49:44 (permalink)
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    I sanded the flywheel and coil legs while I had the coil removed. Set the gap to my business card but still no spark. AVB what were your last two thoughts? I should make sure to ground what? How do I determine if it is an L-head?
     
    It's really grinding me that this engine worked 6 months ago, went into a shed, and is now being stubborn.
    AVB
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    Re: No Spark - 5HP Front Tine Tiller 2020/03/30 09:17:09 (permalink)
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    blaubner
    I sanded the flywheel and coil legs while I had the coil removed. Set the gap to my business card but still no spark. AVB what were your last two thoughts? I should make sure to ground what? How do I determine if it is an L-head?
     

    What about the coil grounding is two fold.
    1. First remove the coil's kill wire to see if there is short in the coil's kill circuit. Try starting with it disconnect. If you know have spark then there is a short in the wiring to ground.
    2. Sometimes the coil mounting post become corroded and loose the the coil's ground connection to the engine.
    As to rather it is L-head or not. Is an OHV engine or not? Model and type numbers can use to determine this. It also help us to determine if you have old points or new Magnetron ignition system. With old points system it could just dirty points contacts.
     
    It's really grinding me that this engine worked 6 months ago, went into a shed, and is now being stubborn.

    Don't fret here as I have seen them to fail here right after a lightning storm. I had one that was the evening the mower came in, then the storm overnight. The next morning no spark. Electronics are strange that way.
     
    blaubner
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    Re: No Spark - 5HP Front Tine Tiller 2020/03/30 10:12:56 (permalink)
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    Update:
     
    Model: 135202
    Code: 9406292D
    Type: 011901

    Not sure how old the machine is. The model, code and type were on the flywheel guard. Confirmed that the spark plug I'm using is the correct replacement (champion J19LM), and assuming the plug came with the correct gap out of the box (0.030 inches).

    With the plug removed, I was not grounding the plug to the cylinder fins as AVB suggested. I tested with the plug grounded and now see a spark.

    I suppose that rules out an electrical problem?

    So now I have a spark but the engine still does not start. I've already familiarized myself with how to remove the carburetor. When I looked at the carburetor while removed it looked pretty clean inside, but I also don't know what to look for there.

    Where should I test next?
    Roy
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    Re: No Spark - 5HP Front Tine Tiller 2020/03/30 11:17:57 (permalink)
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    The code indicates 1994, sixth month 29th day, it is an Lhead (valve in block). With the blower housing off spin the flywheel backwards by hand, it should hit compresion and bounce back. Also check the carb diaphragm, it may be hardened with age.
    blaubner
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    Re: Spark present, still not starting - 5HP Tiller 2020/03/30 13:01:19 (permalink)
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    Is the diaphragm the rubber piece that sits beneath the carburetor and on top of the gas canister? When I removed the carburetor from its mounting, that rubber piece was really old. 
     
    I figured that rubber piece was kind of insulator. What is it's function?
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