Kohler Command HO 16 horse has a miss

Discussion in 'Mechanic and Repair' started by hammmerhead, Sep 8, 2010.

  1. hammmerhead

    hammmerhead LawnSite Senior Member
    from ozarks
    Posts: 266

    I have a 1999-2000 Dixon with the Kohler engine. It has had a mind of its own for years now. It runs perfect, then runs like crap. When it is missing it happens at idle as well as wide open. I changed the coil and spark plug a couple years back that didnt help. I have had the carb off several times, no trash in the bowl and it is never empty when checked and all vents, pickup tubes seem to be clear in the carb. The needle and float seem to be fine as well. I have had the fuel tank off and it had zero trash and the metal mesh filter was shockingly clean for so many years of use. Very rarily will the engine completely die, but it has done that in the past. The engine is clean, never needs oil added and its barely dirty at the end of the season. I asssumed it might be the fuel pump but it seems to hold good pressure as I have removed the line to make sure. Under a really good load in thick grass it will actually back fire sporadicaly while it is missing. It seems like a lean condition because there is no excessive black smoke from too much fuel. I have adjust the idle mixture all over the place and it doesnt solve the miss. Its aggravating because sometimes it will run flawlessly and then the next week it will have its miss as soon as I start it up. I guess my first move will be a new fuel line and clear filter to confirm fuel pressure, although I dont think its the issue having such good fuel delivery after checking it. Next the smart spark box or whatever they call the advance module which is pretty expensive. I just hate to have to take it somewhere and get 10 things replaced before they actually figure out what it is. I really like this little mower, but I am moving to a bigger yard and dont want to have put up with this any longer. Any of you Kohler gurus have any ideas? Thanks for your help!
     
  2. rwaters

    rwaters LawnSite Senior Member
    from Online
    Posts: 731

    we would need more info to really help you, like model of the engine and if it is a twin or single.

    if it is a twin does it always miss on the same side or does it move

    if it moves take it to a shop and have them take a look at the carborator, I have had one with a crack have a traveling miss before.

    the other thing I am thinking would be the coil if it only happens after you use it for a while. but as I said we would need more info to give you good advice. hell for all I know right now it could be a fuel filter or a spark plug.
     
  3. hammmerhead

    hammmerhead LawnSite Senior Member
    from ozarks
    Posts: 266

    Its a single cylinder 1999-2000 16 horse Kohler command HO. (Dont have model number right now, Im at work) Has a good blue spark when the plug is pulled. Carb has no cracks, I think its a Walbro carb. Fuel tank was off this spring no trash in fuel filter and seems to have good fuel pressure. I noted it my post sometimes it runs great for an hour and sometimes the miss is a soon as it fires up cold.
     
  4. hammmerhead

    hammmerhead LawnSite Senior Member
    from ozarks
    Posts: 266

    I replaced the fuel line today and added an inline filter so I could make sure it was getting fuel. The motor fired right up and filled the filter approx. half full. After I let it warm up for a few minutes it started missing again. I looked at the filter and it was empty. I could see air surging through the filter in time with the miss. I removed the pump and couldnt find any tears in the diaphram and although it wasnt flat and looked stretched out a bit (maybe that is the way it supposed to be). I can work the arm on the pump and it seems to hold suction fairly well without leaking down. I guess its not working when it heats up or I have another issue. Anyone heard of a pump working good cold and then failing after the engine gets warm?
     
  5. timberattler

    timberattler LawnSite Member
    Posts: 7

    Hammerhead...have had this issue more than once. There is a grommet that connects the fuel line to the tank. Remove and replace it. Even though my tank didn't drip gas, there was enough slack there that would allow the fuel pump to pull air instead of fuel.
     
  6. hammmerhead

    hammmerhead LawnSite Senior Member
    from ozarks
    Posts: 266

    Very interesting Timberrattler and thanks for posting. Im picking up the new pump today and will give it a go this weekend. I removed the screen filter from the tank plug and added an inline filter futher down the fule line. Hopefully I wont need a new plug for the tank, but atleast it wont break the bank If I do need it and it will be an easy fix. Thanks again for the heads up on that.
     
  7. hammmerhead

    hammmerhead LawnSite Senior Member
    from ozarks
    Posts: 266

    Well, back to the drawing board. Mower ran great for 5 minutes and then started sputtering and died. Fuel filter showing fuel and it wouldnt hit a lick. Had to let it cool down before it would start again. When I tried to start it while it was still warm it would jut let out a big single backfire every now and then. This crap is getting embarrasing. Im sure my neighbors are making home movies of me monkeying with this mower. I tried a shot of starting fluid and it still wouldnt do anything. Inbetween new coils and recently a new fuel pump, I dont know whats next. Anyone think the spark advance module could be it? Granted, this engine is going on 11 years old and it has been a good one in my opinion, but I really think this will be my last Kohler as my Briggs and Kawasaki engines are just as old and still giving trouble free operation.
     
  8. The Lawn Ranger CT.

    The Lawn Ranger CT. LawnSite Member
    Posts: 194

    I see that you've checked just about everything so far with no luck...
    Have you checked the kill switch leading to or from the coils to see if any have woren through~? You might want to disconnect them and see if it runs any better~? Its worth a shot,...I had a Kaw 17hp twin that one of the wires wore through and would hit and miss everytime it would shortout while it was running. Hope this might help ya.
     
  9. hammmerhead

    hammmerhead LawnSite Senior Member
    from ozarks
    Posts: 266

    Thanks for the note LawnRanger. I just pulled the spark plug and it was wet with fuel, grounded it and it only sparked three times or so when cranking it over for about 7 or 8 seconds. This would explain the single backfire I have been getting when trying to start it. By this time I had to hook up my battery charger and when I turned it over again it started sparking normal....then it started the sporadic spark again. The engine is in an old Dixon mower which has tons of safety switches on it. You say the white wire is the kill wire on the coil?
     
  10. hammmerhead

    hammmerhead LawnSite Senior Member
    from ozarks
    Posts: 266

    I just checked the coil...or at least I think I did. Set my meter at 20K Ohms. put the positive probe in the spark plug boot and touched the neg probe to bolt that holds the coil down. I tried grounding the probe in different spots on the coil and got the same reading of 624. Anyone know If its good or bad?
     

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