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kohler 26 and 28 efi problems

Discussion in 'Mechanic and Repair' started by goulding.c, May 26, 2008.

  1. goulding.c

    goulding.c LawnSite Member
    Messages: 17

    I have 2 mowers with kohler command motors 26 and 28 efi. One is acting like a tps sensor is going in it with a code saying its running to lean, when the sensor is reset it last for half a day then the mower cuts out as soon as it turns down hills and then just alltogther, even after a new sensor was installed. do you guys think I should replace the o2 sensor, now? I was told at the dealer that it may need an entire new intake manifold due to wear on the shaft that goes into the sensor. I am just tired of driving it back to the dealer every week waiting for 2 days and still not having a working mower. Any advice??? Can I run the machine bypassing the o2 sensor to see if it changes anything? Thanks
  2. goulding.c

    goulding.c LawnSite Member
    Messages: 17

  3. Richard Martin

    Richard Martin LawnSite Fanatic
    Messages: 14,699

    Disconnecting the O2 sensor will put the EFI into closed loop and it should run but not optimally. It should run so well that you'll think the problem is fixed.
  4. tallimeca

    tallimeca LawnSite Bronze Member
    Messages: 1,229

    i've never had to replace a TPS sensor on an efi......however, the sensor is part of the throttle body, not the intake manifold.

    That being said, is your dealer running through the diagnostic process that the bosch software supplies? Or , are they pulling a code, replacing a sensor and sending you on your way?

    02 Sensors are the most common however, the engine usually won't die because of a bad 02. Tell them to run the diagnostic, which could take a couple hours to do correctly, but it would cut out the possiblity of broken wires, bad grounds.......ect.

    I've seen some weird things happen with fuel pumps on these. Turn the key on, you hear them cycle, and it will run, but won't build enough pressure to keep it running. If you pull the fuel line off and cylcle the key on, it should shoot fuel like 20 feet out the pump. If it's not doing that, the pump isn't up to par.
  5. goulding.c

    goulding.c LawnSite Member
    Messages: 17

    The fuel pump is fine, runs with key on engine starts and can run at full throttle for half an hour sitting there. If you drive away, any hard bump or right turn cuts engine spark out and then it re fires just before dieing. The mower is sitting in our shop now with no reliable service garage near by, due to the closing of the local kohler dealership. No codes are on the led other than the normal condition code????:confused:

    Any advice?

    MS_SURVEYOR LawnSite Bronze Member
    Messages: 1,002

    Yea. Find a good service shop. Call Kohler for a location.
  7. Richard Martin

    Richard Martin LawnSite Fanatic
    Messages: 14,699

    Have you checked the rollover switch? Perhaps it has a low oil sensor that is cutting the engine off. Turning and hard bump cutting out are not an EFI symptom. They are electrical issues. Try taking all of the connections apart, cleaning them with contact cleaner and then put a small amount of dieelectric grease in each one. Is a safety malfunctioning?
  8. anthonyslandscaping

    anthonyslandscaping LawnSite Member
    Messages: 65

    also check the brake switch
  9. fixer67

    fixer67 LawnSite Silver Member
    Messages: 2,098

    What machine is this one? I had a Walker that acted like this just to fine out I had a pinched wire in the harness. It only acted up what you made a sharp turn.
  10. ricky86

    ricky86 LawnSite Silver Member
    Messages: 2,122

    Check the fuel pressure. Should be 39-40 psi. Disconnecting the O2 sensor will put the system into open loop, not closed. Meaning it can't adjust mixture due to lack of signal. It should have been replace at about 600 hrs, anyway. And yes, it will last longer, so I don't want to start a meaningless debate on that subject. If replacing the TPS, especially on a CH-26, the manifold should be replaced. What code is it spitting out??? You said it had codes then you say it doesn't. And, complete faith shouldn't be put in the diagnostic software. It's just another tool. Nothing more.

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