28 H/P Kohler EFI

Discussion in 'Mechanic and Repair' started by ricky86, Jun 6, 2009.

  1. ricky86

    ricky86 LawnSite Silver Member
    Messages: 2,139

    Anybody experience this problem with a CH745S. Starts fine. Idles fine. High speed - no load, engine surges violently. Engage blades, engine run fine. You can have blades engaged and reduce throttle to idle and engine wont stall. It will also accelerate cleanly from idle to high speed with blades engaged. No codes in memory (of course not). Gov adjustment has been verified and spring has been tried in different positions. When running, gov action/strength was compared to an identical unit. Seems the same. If the idle speed adjustment screw is turned in to various RPM's there is no surging. Overall condition of engine is good. 40psi on fuel rail. Has had fuel filter serviced regularly. Sometimes, I just hate advancements in technology.
  2. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    What is the high speed no load RPM set at ?
  3. ricky86

    ricky86 LawnSite Silver Member
    Messages: 2,139

    3750. Tried varying rpms. Surge kicks in at 2300. Adjusted gov as outlined in manual. I have a feeling it's a fuel system problem.
  4. VegetiveSteam

    VegetiveSteam LawnSite Senior Member
    Messages: 296

    Are you getting spark on both cylinders? If there are no codes and you're getting good spark on boty cylinders I would initialize the throttle position sensor. Instructions for doing that can be found in section 5B of the repair manual pages 5B.9 and 5B.10. The repair manual can be found at www.kohlerplus.com under service literature.
  5. ricky86

    ricky86 LawnSite Silver Member
    Messages: 2,139

    That was done after the governor adjustment was performed, but thanks for the input. I leaning toward possible air leak somewhere, but I 've seen an EFI run fine with one intake gasket sucked 3/4 in. If there is no leak, I think the TPS/manifold assy will be the first waste of money. I don't believe it could be both injectors. This just started happening.
  6. stevesmowing

    stevesmowing LawnSite Senior Member
    Messages: 847

    What was the issue? I have the exact same problem with my machine.
  7. Realslowww

    Realslowww LawnSite Bronze Member
    Messages: 1,527

    Good luck here, that was like 5 yeas ago.

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