Kawasaki FH770D 28HP sputtering under heavy load

Discussion in 'Mechanic and Repair' started by lotsagrass, Aug 17, 2012.


    BIGDOGMN73 LawnSite Member
    Posts: 32

    Did you ever figure this one out? I've got the same type of issue with mine.
  2. lotsagrass

    lotsagrass LawnSite Senior Member
    Posts: 650

    I just got the parts today (2 new coils and new plugs). I don't need to mow right now but I took it out for a test run in the field where the grass is tall (usually mowed with the tractor every month or two). I only ran it for about 20 minutes, but so far it runs great. No sputtering and no backfires. It plows throw the grass as I'd expect with just a little bogging down of the engine in the really heavy grass. I'll probably need to mow this weekend so I'll keep an eye on it and see if there's any more issues. I hope this solved the problem. I think it did. I think the reason why it ran better the last time I put the carb back together was because I put some octane booster in the gas so I think it was able to run a little stronger than it normally would...but then the backfires started and more sputtering. After putting the new coils on today though, it runs good. We'll see what happens. I'll update again if anything comes up but I sure hope I'm done! Overall it's about $125 in parts and about 2 hours or so of labor. It was sort of a pain to adjust the clearance of the coils to the flywheel magnets, but with a little care and adjusting each side of each coil (by myself) little by little, I got it in the middle range of the clearance the book says is recommended.

  3. cgaengineer

    cgaengineer LawnSite Fanatic
    Posts: 15,782

    Next time just fold a piece of copy paper about 2-3 times instead of using feeler gauges...they also make brass feeler gauges. The air gap is not super critical (ill probably catch hell for saying this)

    Saw you were using the brass gauges...you can unscrew them from the holder so you can span the coil....
    Posted via Mobile Device
  4. lotsagrass

    lotsagrass LawnSite Senior Member
    Posts: 650

    I guess I don't know all the shortcuts/tricks since I don't do this all the time. My father was a lifelong mechanic so I picked up some knowledge from him, but we're not very close so unfortunately I didn't learn all his good info.

    Oh by the way, I couldn't resist another run this evening. I went out to the field again and mowed for about 30 minutes in tall/thick grass. The engine runs really strong and smooth. Sounds/runs great. :)

    BIGDOGMN73 LawnSite Member
    Posts: 32

    I wish my mower was the same. I updated my ignition coils and it seems worse.
  6. lotsagrass

    lotsagrass LawnSite Senior Member
    Posts: 650

    I mowed for 2.5 hours today and it runs perfectly. Very strong and very smooth. I think it's safe to say at this point it was definitely the coils. At just under 150 hours of use on this machine, I never would have imagined the coils would be bad.

    Thanks for everyone's suggestions/help. :)
  7. LarryF

    LarryF LawnSite Bronze Member
    Posts: 1,171

    I had the same experience and is why I had a hunch it was your coils. Probably it was just one of them. Glad to hear that you got it resolved.
  8. piston slapper

    piston slapper LawnSite Platinum Member
    Posts: 4,245

    Ditto...taking the gauges out of the holder makes them a lot easier to use...
    I use the foot long feeler gauges made for working on diesel engines..they span the coil every time...not too expensive...if you don't want to buy the whole set you can usually buy the individual feeler gauges from SnapOn or Mac Tools..
    Posted via Mobile Device

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