black smoke on startup. Diagnosis?

Discussion in 'Mechanic and Repair' started by brucec32, Jun 2, 2006.

  1. brucec32

    brucec32 LawnSite Platinum Member
    Messages: 4,403

    I have an exmark lazer with a 23hp kawi. It has about 200 hours. Recently on start-ups I get a small cloud of black sooty smoke. Otherwise it runs strong. Oil level is correct.

    I assume this is from some sort of rich fuel mix situation? What do I need to look for in terms of problems? Could it be the choke not returning to the fully open position? Should I check the plugs?

    Your ideas appreciated.
  2. rickt

    rickt LawnSite Member
    Messages: 47

    Might want to check your spark plug, if you replace it or it still looks ok drain all the gas and add a little back and add about a spoon-full of gas treatment (aka carb cleaner - from walmart) and it should fix your problem. I had a mower that always shot out black smoke and after i ran some gas treatment through it, it stopped. Im not sure what it was to begin with.
  3. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    The first thing to check would be the choke, Then look at the plugs and see if they are black. Do you haul this unit around on a trailer ? Do you shut the fuel off while pulling ? Could be bouncing around and flooding.

    Also there is a service bulletin on the air filter, I posted it here; Go to post 3
  4. brucec32

    brucec32 LawnSite Platinum Member
    Messages: 4,403

    Thanks. Yes, it does get some bouncing in on the trailer from time to time. I cable it down rather than use straps. I have had some previous fuel filter problems with this and another Kawi engine so I will check that too.

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