Got a x540 law tractor with a 26hp Kawasaki liquid cooled motor. It all started when the owner was mowing there lawn and it started surging but they decided to run it a few weeks that way until it just wouldn't run any longer . I go there and do a general tune up (air filter, plugs, fuel filter ) the fuel filter plugged up with grass . Took the carb apart and cleaned it . Had grass plugging up the main jets . Put it all back together and runs good . Fast forward to the other day, I get a call saying it's doing the same thing . I pick it up and it runs beautiful . I take it anyways and rip it apart. Take all the fuel lines off and blow them out . Take the gas tank off and slosh it around and run it threw a paint strainer. I was surprised it even ran . Had sticks , leaves , pine needles , pine cones and grass in it . I did that until it kept coming up clean . I clean the carb again just for good measures and it's clean as a whistle. I went out to start it and it was acting up . So I take out the fuel shut off and looked up how to test it . It checks out . It isn't acting up now so I can't troubleshoot it at the moment but I did notice a few things . The fuel filter looks like there is hardly any gas in it while it's running, also when I turn the mower on it seems like it almost dies then picks up and runs good . I was hoping some one that had one of these could tell me if that's normal or not . Sorry for the long post