26 HP Kohler EFI engine spitting black smoke

Discussion in 'Mechanic and Repair' started by GRSHPRLC, Jun 30, 2008.


    GRSHPRLC LawnSite Member
    Messages: 2

    Hi all!
    I have a 2001 Exmark Laser Z, it has a 26 HP EFI on it. Lately it has been sputtering and blowing black smoke. We thought that the sputtering was water in the fuel, so we added dry gas to the mower. It worked for a couple days, but is doing it again. Any suggestions? Could this be caused by a bad CO2 sensor?
  2. Two Seasons

    Two Seasons LawnSite Senior Member
    Messages: 791

    Bad O2 sensors in cars make them default to a rich fuel condition, but I'm not sure that this is what Kohler programmed for your engine.

    If you disconnect the plug at the O2 sensor and the condition (black smoke) remains the same, you may have your answer.

    GRSHPRLC LawnSite Member
    Messages: 2

    ok, so I disconnected the O2 Sensor. Still ran the same. Replaced the O2 Sensor, mower runs the same! Anyone have any other ideas?
    Fuel pump, maybe?
    It only does this when the PTO is engaged.
  4. Oldtimer

    Oldtimer LawnSite Bronze Member
    Messages: 1,459

    It needs to go to a Kohler dealer who has the software to diagnose the problem. It's the only way.

    We were a beta site for the Bosch software when Kohler began production of the EFI 26hp engine.


    MPOSSIBL LawnSite Member
    Messages: 7

    i have a Walker mower with the EFI 26 hp engines, and about 2400 hours and that unit has been a lot of trouble, and the past 2 days it is acting up again.
    As far as your situation, to determine the issue with the msfiring , turn the ignition key rapidly 3 times : on/off/on/off/ on, and leave it on at the third time, your "service engine soon" light will come on three times , pause then another number of times , if it blinks 3 times then 1, it is oxygen sensor, BUT it may not be the cause of your problem, last issue i had i was doing the same thing, come to find out, it was a tiny crack in the fuel line, that craeted the misfiring !!
    if you had a tiny air buble lodged in the fuel pump it could create the same thing : misfiring, use compressed air to pressurize the fuel tank while runnig therefore pushing the air bubble out, to do that all you need is a rag and a nozzle , insert lightly the air nozzle in the tank and seal it with a rag, its better to have another person to help.
    i would rule out the fuel pump , bcoz it works or does not !! and if it doesn't : your machine would not run at all. .GOOD LUCK MATE

    MADMANDAN LawnSite Member
    Messages: 23

    Check For A Loose Or Damaged Wire To The O2, And First Things First! Did You Check The Air Filter?

    MPOSSIBL LawnSite Member
    Messages: 7

    come to find out, my fuel pump is pushing only 20 to 25 psi at best instead of 39 psi, creating misfiring, need a new one , $180.00 !!!!!
    2nd one in less than 2 years, i am going to sell this EFi !!
  8. bike5200

    bike5200 LawnSite Member
    from Ky
    Messages: 55

    I have the Kohler EFI, about a 1 1/2 years ago not running good. Had about 650 hrs on it. The dealer put a updated wiring harness that has more grounds on it. They had to replace the O2 sensor. When the O2 sensor was replaced the mechanic screwed up the muffler, so had to buy a new muffler. Put new injectors in it, which they have to pulling the engine. Replaced the spark plugs I had just replaced two week earlier. After about $1200.00 it was fixed. Still running OK, knock on wood. Not happy with the engine
  9. sawman65

    sawman65 LawnSite Senior Member
    Messages: 754

    too many shade tree dealers out there if you have an efi engine you need to take it to a dealer that has the software to fix it plain and simple. if there is not one near you that has it call kohler. they WILL step up for you. i had a guy in nc. that was having problems but was 70 miles away and no one could fix his kohler i sold him. the kohler rep went to his house only to find a bad ground(common in these engines). do what oldtimer and me suggest. unless you just want to throw parts at it till you stumble upon the problem.

    MPOSSIBL LawnSite Member
    Messages: 7

    i understand with the software, but i saw myself that the fuel pump was only putting out 20 -25 psi, after barely starting at 30 psi, and the pump should put out a constant 39 psi. Just to add : i never had any trouble or any kind of issues with my other mowers with the Kohler 20hp, and its about to reach 3000 hours on one of them, i cannot say the same about the EFi, which had problems from just about day 1 . All the repair costs offset the gas savings, for sure ! Sorry to say, my next walker will have 23hp or 25 hp water cooled. Thats my story and I AM STICKING TO IT !!

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