Carb question about toro gts (gtx?)

Discussion in 'Mechanic and Repair' started by matthew horner, Feb 7, 2006.

  1. matthew horner

    matthew horner LawnSite Senior Member
    Messages: 696

    I have an early (i think) 90's model toro 21 incher. Its got the suzuki motor.
    I went to tune it up this year after an employee last year said it would not start. It was late in the year so we just quit using it.
    Well, i tuned it up and it started. When I took it off of choke it "surges".
    Whoom, whoom, whoom, from one extreme to another. There is a lever that is moving with the whooms??? that if I hold it makes the engine scream. It looks like it is connected to a butterfly valve in the carb ( I suspect regulating the amount of fuel in. So, 1. why the surge, and 2. how do I adjust it or otherwise repair it so that it runs smooth?
  2. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    The surge is probably because the carb. is gummed up and not letting enough fuel through (leaning out). The fix is removing the carb., Disassemble, Clean with carb. choke spray cleaner spraying out all passages and jets then reassemble and install back on the engine.
  3. matthew horner

    matthew horner LawnSite Senior Member
    Messages: 696

    Hmmmm, I figured it would be an adjustment. I'll clean the carb. BUT- how does it know to surge? Like I said, if I move it manually, it runs out fine.
  4. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Below will give you a basic idea how a governor system works, When a carb. leans out the rpm drops and the gov. tries to give the engine more fuel which it can't because there is a lack of fuel so the gov. tends to cause the rpm hunt.

    Attached Files:

  5. lawnboy dan

    lawnboy dan LawnSite Gold Member
    Messages: 3,711

    these minkuni carbs are very touchy about tolerating dirt gum etc. they must be keep extremly clean to run right. be carefull not to bend the linkages any more than you have to when removing carb as adjustment will be off when you put carb back on. i leave my munkinis on the engine and take them apart and spray carb cleaner tru then blow out w/compressed air (dont forget idle passage jet)this usually is all it takes to clean one out
  6. Dallas Turf

    Dallas Turf LawnSite Member
    Messages: 245

    If it is a real old machine check the tip of the throttle shaft under the butterfly. I have seen these wear way down and cause this problem.
  7. matthew horner

    matthew horner LawnSite Senior Member
    Messages: 696

    I took it off and cleaned it up really well. When I put it back on, the same problem. It runs fine when chocked. I guess I'll try to clean it up again. Is it of note that when it is "searching" if I spray carb cleaner in the intake it runs fine till it burns the carb cleaner and then goes back to surging? Does that pretty much show it is not getting enough fuel when it wants through some port?
    Thanks so much for the help so far.................matthew
  8. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Messages: 2,248

    Two other areas to check are the pilot jet in the top of the carb and wear in throttle shaft on the top side. The pilot jet has a very small hole and should be cleaned with a very fine wire(I use wire from braided cable as found in toro One and clutch cables). To check for wear in the throttle shaft I sauirt a flammable carb/chole cleaner/starter fluid on the top end of the throttle shaft. If the engine evens out when squirted as above you likely have excessive wear. In that case you will need to replace the throttle shaft. Likewise as stated above, wear on the botton of the throttle shaft will cause the butterfly to hang up on the carb throat.


Share This Page