Kohler 25 backfire

Discussion in 'Mechanic and Repair' started by burlap, Jul 26, 2006.

  1. burlap

    burlap LawnSite Member
    from Indiana
    Posts: 66

    I have a Koler 25 that seems to be running one one cylinder. If I pull the spark plug wire while it's running the engine doesn't seem to change much when one is pulled and the other side barely runs and dies when I pull the other. I seem to be able to see spark with a tester and I am using new plugs. I've done a lot of searching and wonder about the coil. How difficult is it to get to the coil. This is on a Snapper ZTR. It has about 450 hours on it and I was wondering if I change one coil should I change both? I have no idea what a coil would cost. In my search so often I hear people say it missed under load-but that isn't the case with mine. It runs better with a load. It backfires quite abit just driving it with the blade not in gear or with it throttled down. I did a pressure check and they were both about 150. Any ideas? burlap
     
  2. Jim@MilkyWay

    Jim@MilkyWay LawnSite Senior Member
    Posts: 472

    I Don't know what your engine is suffering from, but the answer to the question is ..no.
    Failure of these devices is not necessarily tied to the number of hours of operation. Meaning that one coil can out-live another by a factor of several to several-tens of hours, months, or even years. The only coil I have ever replaced (residential) was because I did not want to hassle with ignition points any more. That coil, by the way was still good, but the mag kit includes a new coil.
     
  3. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,022

    You have to remove the grass screen then the flywheel cover to gain access to the coils, Then using a multimeter perform the following test.
    Look on your old coil for the part number for the proper specs.,
    Also Kohler states to replace both coils at the same time depending on the part number on your old ones and the serial number on your engine.
    I will see if I can dig that info. up and post back.


    [​IMG]
     
  4. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,022

    OK here's what they say about replacing both;

    Command Coil Replacement.jpg
     
  5. Jim@MilkyWay

    Jim@MilkyWay LawnSite Senior Member
    Posts: 472

    There you go!
    See there; I told you to replace both!:)
     
  6. Jim@MilkyWay

    Jim@MilkyWay LawnSite Senior Member
    Posts: 472

    _THAT_ is good, potentially very useful to know. It ranks up there with..."don't jump start EFI equipped engines".
     
  7. Jman

    Jman LawnSite Member
    Posts: 217

    What spec number is it?? New spec 25 horsepower engines (CH730's) don't use smart spark ignition and therefore only one coil would need to be changed if there is no spark on the one side.
    Question I have. Is it backfiring out of the muffler or popping back thru the air filter? If it is thru the air filter,pull the valve cover on the side that has no change, check for brocken rocker arms or bent push rods. Also, spin the engine over and make sure the rocker arms open the valves equal amounts. If the exhaust valve doesn't open, due to a flat cam lobe, you will get a pop back thru the air filter.
     
  8. burlap

    burlap LawnSite Member
    from Indiana
    Posts: 66

    The spec # is 68577 and I think I can see the smart spark box on the cover opposite the fuel pump. When it backfires it comes out the exhaust because I can see a puff coming out at the same time. I can't really give you a color, but I assume it is residue from the ignition in the hot exhaust pipe.
     
  9. Jman

    Jman LawnSite Member
    Posts: 217

    That is a unit that does have smart spark ignition. Follow the guides above for resistance tests.
     

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