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lawn-boy woes

Discussion in 'Mechanic and Repair' started by calhoontuna, Oct 18, 2005.

  1. calhoontuna

    calhoontuna LawnSite Member
    Messages: 7

    Still working on my M-Series Lawn-boy. Two stroke. Can't get it started. I pull and the thing doesn't turn over.

    Somewhere I read that you can trouble shoot by throwing a little gasoline directly into the carburator throat or into the spark plug hole. They say that if it starts then you know that the problem is related to gas delivery. However, no one talks about what happens if the mower still refuses to turn over -- which is what I'm running into. (found a brief, brief reference somewhere that it might be related to a crankshaft seal under the muffler, but I removed the muffler and there is no such thing).

    If you throw a shot of gas directly into the cylinder and the thing doesn't run briefly, what is that telling me? What can I check out.

    Thank you for your time,
  2. Jason Rose

    Jason Rose LawnSite Fanatic
    Messages: 5,858

    Are you getting any SPARK??? That's the first thing to check. DON'T FORGET, the M-series has 2 electronic saftey switches. 1. where the metal frame of the grass catcher, or the metal 'hook' on the mulching plug sits infront on the peg on the right rear side, top of the deck. 2. is a kill switch IN the oil resivour. If you have oil in it at least 1/4 full or more and the grass bag is in position and you still get no spark try unplugging the sensor in the oil tank. Small plug inline the wires under the tanks on the backside of the engine. Unplugging it will disable the sensor and allow the mower to run even with no oil, so be careful with that...

    The oil sensor went out on mine a few years ago. Mower would run like a top one day and would not start at all (no spark) the next. Fianlly messed with it and discovered this to be the problem. It now runs fine without the sensor in the tank. It's easy enough for me to see the oil level and add some on occasion. I think the oil injection for 2 strokes was the smartest invention ever but for some reason it never cought on. I love my M-series and still use it today when I need it.
  3. grass_cuttin_fool

    grass_cuttin_fool LawnSite Gold Member
    Messages: 3,526

    If It wont start at all, Then I would check the spark, there is a tool that checks to see if you have voltage on the spark plug wire.
  4. TLS

    TLS LawnSite Fanatic
    Messages: 7,943

    Engine won't turn over = Engine seized. Likely from regular gas use. Stick a wooden dowl in the spark plug hole and hit with a hammer to attempt to free it up.
  5. lawnmaniac883

    lawnmaniac883 LawnSite Silver Member
    Messages: 2,613

    Do you mean it wont turn over or wont start? Big difference!
  6. TLS

    TLS LawnSite Fanatic
    Messages: 7,943

    Sounds like it's siezed to me. Not turning is siezed.
  7. calhoontuna

    calhoontuna LawnSite Member
    Messages: 7

    Sorry. Should have mentioned that I am in fact getting a spark. When I ground the plug against the head and pull the cord slowly I can clearly see a blue spark.

    In fact, that's what started this whole thing. The plug wire went bad so I had to replace the magneto. Used a match book to gap it (which I was told was the appropriate gap). I also tried a number of different gaps as well just to be sure. None worked.

    Also, the flywheel key is fine. Replaced it just to be sure.

    I took off the carburetor through the hole I can see the piston moving when I pull the cord. That would rule out it being seized, wouldn't it?

    As for not turning over versus not starting, I don't get anything. Pull the cord and the thing is dead, no cough, no sputter, nothing. With that said, the thing will backfire on a few random pulls.

  8. TLS

    TLS LawnSite Fanatic
    Messages: 7,943

    NOT SIEZED then.
  9. lawnboy dan

    lawnboy dan LawnSite Gold Member
    Messages: 3,711

    did you replace the ignition module with a new one or a used one . these are famous for going bad . if you have spark you should get the motor to at least sputter when putting gas into the spark plug hole. instead of gas use starting fluid. this is less likely to flood the engine and is more flamable than gas so if there is spark -motor will fire. use a new spark plug also . proper troubleshooting requires that you remove as many varaiables that you can. the gap for the module is .10 -i use a buisness card and it always works fine. is there compression? put your thunb over the spark plug hole -you should feel suction as you pull the starter cord
  10. calhoontuna

    calhoontuna LawnSite Member
    Messages: 7

    Yea, it was a brand new module.

    I was wondering about the compression myself. If I put my thumb over the hole I do feel some pressure, but not enough to blow my thumb off the hole.

    I will try some starter fluid tonight.


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