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kawasaki fb460V stalling

Discussion in 'Mechanic and Repair' started by kmd, Sep 17, 2004.

  1. kmd

    kmd LawnSite Member
    Messages: 2

    I have an old gravely pro 40 walk behind 12.5hp kawasaki fb460V, the motor will start fine and will run forever not in gear or with blade de-activated, I can activate the blade and it will still run forever, when I put it in gear it will run fine for about 30 seconds then it will start to konk out every once in a while it will catch itself then konk out a few seconds later. I think it is the carb it sounds like to me there is a problem with the float of needle valve. This is what I have done so far:

    1. pulled carb apart and cleaned it out best I could with carb cleaner and put it back together 4 times.

    2. new spark plug and air cleaner

    3. did compression test screw in type first pull 50psi, if I pull again it gets to 75psi

    4. changed inline filter and put new gas in tank made sure I had good gas flow down the line to the carb.

    If this was an ignition problem it usually works or it doesnt, A new carb is $130 dollars it seems like a pretty simple design I dont know why me cleaning it out doesnt seem to work but I dont know what else it could be what do you guys think? I would hate to buy a new carb and find out that isnt the problem, if my valves were messed up I would not think my compression would be that good. Any helpful hints would be appreciated thanks
  2. Travis Followell

    Travis Followell LawnSite Silver Member
    from KY
    Messages: 2,206

    It sounds like to me that it is a fuel problem. When the engine gets a load on it like the wheels and deck turning the govenor should open up. I would suggest that you check the govenor to see that it is working properly.

    Will it run ok in gear with the deck off?
  3. kmd

    kmd LawnSite Member
    Messages: 2

    I didnt try that if it does run ok with the deck disengaged and in gear what does this mean? How does the govener operate and what drives the govener? I can see it modulating back and forth not much but a little bit.

    It almost seems to me that the carb can deliver enough fuel if it is just idiling or with the blade engaged but not in gear but then when you put it in gear it wont deliver enough fuel? The only thing is the carb seems so simple you cant adjust the float it is plastic, I made sure the float is not cracked the needle valve seems fine and when I cleaned the carb with carb cleaner the passage ways are all clear.

    when the mower dies from lack of fuel I think if you wait a minuete it will start right up again and run fine until you start cutting grass again then after about 30 seconds of cutting the same thing happens again. Thanks for your reply anyother thoughts before I buy a carb will be appreciated.
  4. barnard

    barnard LawnSite Senior Member
    Messages: 618

    Its either fuel delivery to the carb or restricted main jet circuit in the carb.
  5. Travis Followell

    Travis Followell LawnSite Silver Member
    from KY
    Messages: 2,206

    Your engine has a mechanical govenor which works off of the cam gear that runs off of the crankshaft. The job of the governor is to detect changes in load on the engine and adjust the throttle to compensate for the load. The mechanical govenor works using flyweights on a gear and as the engine speeds up centrifugal force causes the flyweights to open and that puts pressure on the govenor cup which is linked to the throttle and slows the engine down. As the load increases the flyweights spin more slowly so the centrifual force is less and does not pull the throttle toward closed. The position that you have your throttle set controls tension on the govenor spring which helps maintain the set engine speed. I don't know if the govenor on your kawasaki has an adjustment but if it does try adjusting it. It also wouldn't hurt if you replaced the govenor spring. The last post said you may have a restricted jet but if you have cleaned the carburetor that is not likely. Let me know when you get it running good.

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