Kawaski 25 hp Sputtering. Help!

Discussion in 'Mechanic and Repair' started by blaigle, Sep 5, 2011.

  1. blaigle

    blaigle LawnSite Member
    Messages: 4

    I have a Super Z Kawaski 25 hp, 900 hrs, that started to bog down when I engaged the PTO. It quickly got worse and now it is sputtering at high RPM and will stall under a load. I have changed the, air filter, fuel filter and spark plugs, no change. I pulled the plug lead off both spark plugs and it will stay running (barley). I am looking at the coils, they are rusty, flywheel is really rusty. There is a pickup on the flywheel, it has a little rust on it. Maybe a fuel pump? I pulled the only vacuum line I could see off the carb, it goes into the head of one of the cylinders. There was no vacuum. I am down to changing Fuel Pump, Coils, or Carburetor. Any suggestions at all would be great. Thanks, Blane
  2. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    A valve check/adjustment doesn't cost anything and could very well solve your issue.....


    Don't worry about the rust.... It's just a myth that it affects the ignition....
  3. blaigle

    blaigle LawnSite Member
    Messages: 4


    I will try that before I spend any more money, As an update, I cleaned off the rusty flywheel, double checked the spark plug wires for any signs of wear, and loosened the fuel line to the carb (fuel squirted out when I removed the clamp, so I put the clamp back on and figured the pump must be working to have pressure there). Anyways, It ran fine for about 1/2 hour, now it sputters every once in a while when loaded, but I am able to mow.
  4. fatboynormmie

    fatboynormmie LawnSite Bronze Member
    Messages: 1,281

    I was having issues with my engine running similarly to yours.Found the problem was a deteriorated fuel line inside of the gas tank causing issues.It was slightly sucking air at a bad connection, the hose had distorted.Just another thing to check.Thanks Ethanol
  5. themadcutter

    themadcutter LawnSite Senior Member
    from florida
    Messages: 914

    I had issues like that. it was pretty seldom but then all of a sudden it stayed that way.

    turned out my choke was stuck. I basically strapped the choke open and it solved the problem. Really only needed the choke first thing in the morning any way.
  6. MJB

    MJB LawnSite Silver Member
    from Wa
    Messages: 2,869

    Souns like a coil is going. I just went thru this with my 28 Kawi. Turned out the coil was slowly getting weaker and weaker until I could pull a plug wire and it would die some of the time. I decided to replace that coil after a few tests, that took care of it.

    But I noticed a puff of smoke, and some backfire when starting, when I started it several times this week. I decided to adjust the valves (say every 300 hrs) pulled the cover off and there was an oring, and a wire seal loose between the valves. I decided to put it together and have the mechanic changes the valve seats etc tommorrow. Have you adjusted your valves yet?
  7. whosedog

    whosedog LawnSite Senior Member
    Messages: 730

    Our 25 HP kawi on our wright stander ,with only 500 hours was sputtering also.We changed fuel filter,fuel pump,air filter,spark plugs,replaced blades,cleaned the carb still sputtered;so tested compression,checked the coils all good.Our mechanic noticed a bent spring on outside of the carb,he straightened the spring and the sputtering stopped.We probably snagged it on a bush and didn't notice it,till he went through all the other steps and finally figured it out.I don't know why we didn't notice it first, but it didn't hurt to replace all of the other parts;now we have a great running machine.
  8. themadcutter

    themadcutter LawnSite Senior Member
    from florida
    Messages: 914

    When they were working on mine the shops helper told me it was my valve guide and it was gonna need to be replace. He even showed it to me on the engine. The owner got involved (luckily) and said "wait a second. Why isn't 'this' moving." 'This' being a bar attached to the choke.
  9. unkownfl

    unkownfl LawnSite Gold Member
    Messages: 3,837

    If it's running fine without a load and then under a load acts up I think its your fuel system or carburetor itself.
  10. MJ1

    MJ1 LawnSite Member
    Messages: 2

    Blane......I have a 23 kawi that had the same issues as yours. After replacing the coils, adjusting valves, replacing fuel pump and filter, new (correct) air filter, draining the fuel tank....it still ran the same. I removed the carb and dropped it off at the dealer. He told me that they could clean and reassemble this carb without a kit. He charged me $52 labor with tax. I installed the carb and fired it up. Problem gone....it runs like new. MJ

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