F725 is misfiring on one cylinder

Discussion in 'Mechanic and Repair' started by floridaprowash, Aug 17, 2010.

  1. floridaprowash

    floridaprowash LawnSite Member
    Posts: 10

    Hey guys, I have a F725 54' front mower. I rebuilt the engine about a year ago as preventive maintenance and replaced the cam gear and installed new gaskets. It has been running perfect up until yesterday. I developed a misfire on the passenger side cylinder, after finishing the day off, the cylinder fires every few seconds now. I got it home and checked the spark and it was very weak, only making the spark every few rotations. I swapped coils and the problem is still with the same cylinder. I took off the radiator, shroud, fan, etc. and checked the coil inducers (not sure of the correct name) and all the wiring and all seems fine. Any ideas on what it could be? It definitely seems electrical. I have new plugs and even sanded down the rust on the flywheel. Your thoughts? Thanks in advance!! Jason
     
  2. floridaprowash

    floridaprowash LawnSite Member
    Posts: 10

    Btw, its a John Deere with the FD590v Liquid cooled Twin-cylinder engine.
     
  3. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    Sounds like you may have a issue with the pulser coil, Since you have it tore down perform the below test and see what you get;


    [​IMG]
     
  4. floridaprowash

    floridaprowash LawnSite Member
    Posts: 10

    Thank you SO much for the diagram and quick response, I will head back out the the garage and do some testing...... Ill post what I find =D
     
  5. floridaprowash

    floridaprowash LawnSite Member
    Posts: 10

    Do you have the testing specs for the spark plug coils??
     
  6. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    If you swapped coils with no difference run a test on the ignitor;


    [​IMG]
     
  7. floridaprowash

    floridaprowash LawnSite Member
    Posts: 10

    Ok heres a question, its states that I need a special hand tool tester by Kawasaki. I have a digital multimeter. Ive done a little research on this Kawasaki meter and its seems to be analog type meter. I dont want to damage my ignitor as its expensive to replace. Question is, can I use my digital multi meter and what reading should I look for? Thanks!!
     
  8. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    Make believe your digital meter has Kawasaki written on it, There may be a slight difference in readings but a drastic difference will show a faulty part. I've yet to damage a electrical component just because I didn't use specific brand equipment....
     
  9. floridaprowash

    floridaprowash LawnSite Member
    Posts: 10



    Thanks buddy, its a Fluke meter Ive had for years. Thanks again for the diagrams.
     
  10. floridaprowash

    floridaprowash LawnSite Member
    Posts: 10

    Heres what Ive found, the pulser coils check out within specs. The igniter failed. Terminals "1" and "2" was "open" with all other test locations. That lead me to believe the soldering joints may be corroded or cracked. I took the plastic box apart to find lead wires "1" and "2" on circuit board cracked. I just resoldered the joints now and cleaned up the board, tested ok now. Im waiting on the glue to dry and will install it back on my mower. I feel confident this was my problem. Thanks so much for the diagram. I hope this helps others experiencing intermittent misfires in one cylinder. A new igniter is $200 plus, used units are pushing $100. Digging a little deeper and finding the root cause was FREE =D
     

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