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Kawasaki FH770D 28HP sputtering under heavy load

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

  1. lotsagrass

    lotsagrass LawnSite Senior Member
    Messages: 783

    Sorry, one more update. I just wanted to be sure I log everything here for search purposes in case someone else has the same issue in the future. I think the problem IS the carb. Today it runs really bad even at lesser loads and I can't even mow. So I think I made matters worse by taking apart the carb. So I took it apart again to blow it out with compressed air and I noticed I accidentally damaged one of the O rings when reassembling the card. I just ordered more o-rings and a few other gaskets/seals online from parts tree because none of the local dealers I called have these in stock. I'm pretty sure this is my problem. It makes sense. I was actually glad that the problem got worse when I messed with the carb because now I think the problem is definitely pointing to the carb as the issue. I think it was just dirty originally and it was fine for a few minutes after I put it back together...until the o-ring gave out. It was nearly cut in half. Oops....my fault. This is a very simple carb to take apart so it's not a big fear factor when breaking it open....I just messed up and ruined the o-ring. When I get the new ring and put it together I'll update this again :)
  2. lotsagrass

    lotsagrass LawnSite Senior Member
    Messages: 783

    Here's the latest...

    So, I have the carb all cleaned out after taking it apart again. After the first time I took the carb off, it was actually a little worse so I thought I must not have cleaned it well enough. I discovered I smashed one of the o-rings when reassembling it. So now I have the new o-ring and I replaced a few other seals while I was at it. Yesterday when I started out, it sputtered pretty bad again under heavy load (thicker grass, going fast). After about 15 minutes it seemed to clear up and I plowed through really thick grass at high speeds and it was fine. Today I start out and it's sputtering really bad under heavy load (wet grass, thick). I had to stop sometimes to let the engine catch up because it was sputtering so badly. If I babied it and went slow, it was ok...but any big load would cause the sputtering. After mowing for about 40 minutes, it was better. It only sputtered occasionally, under heavy load. After mowing I went out to the field where there was some REALLY thick grass to stress it and see how it ran. Under heavy load it wasn't too bad, but it still ran a little rough and sputtered sometimes....but when I got into some already cut grass that had lots of extra cut grass lying on top (causes a heavy load on the engine), it sputtered really bad AND made a popping sound coming form air cleaner area, as if it were backfiring. Knowing this, do you have any other ideas as to what it the ultimate cause of the sputtering and in this extreme case, the popping noise which I assume was backfiring???
  3. blabarre

    blabarre LawnSite Member
    Messages: 86

    I'm having a similar issue to what you are having. Although mine typically happens at startup and when i turn on the pto. I have a 19 hp FH601V Kawasaki on a JD 717a (300 hrs on my machine). If I can get it to overcome the spitting and sputtering I can usually get it to run wide open the rest of the time I'm mowing, but if I turn it off and restart it, it will do the sputtering all over again. VERY VERY Frustrating. I wish there was a video or diagram which showed how to clean the carb on my unit. I would like to attempt it myself because I don't want to shell out another 100 dollars to clean the carb if it is going to be a reoccurring event.
  4. teckjohn

    teckjohn LawnSite Senior Member
    Messages: 282

    Its possible you have your valves adjusted too tight.



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  5. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,329

    Hmmmm....Teck...not tech...John...
    Are you a paying sponsor on this site...
    Nothing personal...We give FREE advice and info in this forum..
    You may want to try the equipment marketplace on this site...
    One line of advice...followed by paragraphs of self promotion ain't gonna cut it on this forum....
    Posted via Mobile Device
  6. teckjohn

    teckjohn LawnSite Senior Member
    Messages: 282

    since its free ... i wasnt aware it was catagorized

    and Posting the info to help him properly adjust his valves too now.... and i did not charge for any advice
  7. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,329

    If you had been around this site..you would have seen that the Kaw valve adjustments have been posted on this site about 50 times...

    The only one you're helping on this site...is yourself...
    Posted via Mobile Device
  8. lotsagrass

    lotsagrass LawnSite Senior Member
    Messages: 783

    Hey Brian....I see your FH601V manual here: http://www.mymowerparts.com/pdf/Kawasaki-Service-and-Repair-Manuals/

    I got the FH770D manual there too and it was very helpful!
  9. lotsagrass

    lotsagrass LawnSite Senior Member
    Messages: 783

    Here's the very latest, as of yesterday evening. I went to the trouble to take the carb off one last time (since I know how to get it off quickly now LOL....maybe 20 minutes and it's off). I carefully checked every opening, blew it out again and carefully reassembled. I really don't believe it's ignition related unless someone can tell me for sure some reason why it would only do this under heavy load. I would think that a spark is a spark and if the coils/plugs, etc are working, they're just working and there's no reason why they'd behave any differently under a heavy load...BUT the carb definitely behaves differently under a heavy load, by design. I still think it's fuel related somehow.

    Anyway, after the third breakdown/reassembly of the carb, I searched this forum for the backfiring issue. I found some other people talking about bad gas, carb issues, etc. I had the idea to get some more fuel system cleaner just in case there's still something sticky in the carb I didn't get....and I also picked up some Lucas 'not street legal' octane booster and some ethanol treatment. I usually buy the 93 octane gas but the last few cans I've bought were 89 I think. I'm wondering if the gas station I used sold me some bad gas. I don't know.

    I ran the mower with these products in the tank which had about 5-7 gallons left. After running awhile, it sure 'seems' to be doing a lot better. I went back to the field and plowed through the thick 1 foot tall fescue again and I only heard it sputter slightly once in awhile. At this point, unless it just won't run well enough to mow, I think I'm going to keep mowing with it and get gas from a different station and see what happens over the next few weeks. I think the fuel system is about as clean as it's going to get. LOL New fuel filter, new fuel pump, carb cleaned three times, air filters look good, fuel flows fast and free from the pump when the outlet line is removed and checked with the engine running. Not sure what else I can do, fuel related. I'll update this post after the next couple mows and let you know how it's going.

    Regarding the valves, the engine/mower only has about 150 hours on it. I'd hope that it doesn't need to be adjusted already. Given that the problem changed in severity after I started messing around with the carb, I still lean towards it being fuel related....so we shall see :) Time will tell.
  10. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,329

    Lotsagrass...sorry for detracting from your post...
    I believe the first valve adjustment is around 200 hrs...
    Definitely sounds fuel related..are there any adjustment screws on the carb..
    If so..open them up a little and see if it changes the problem..
    Have you looked at the sparkplugs..running lean can turn them white..affect spark..
    Posted via Mobile Device

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