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20hp Kohler Back firing after shutdown


LawnSite Senior Member
I have an 05 Turf Tracer with a 20hp Kohler powerplant. I am starting to notice the tip of the pipe is getting black and the mower is back firing when I shut it off. Besides unusually bad gas mileage it runs fine. I can sometimes see a small thin cloud of black smoke when it's under heavy load.

Any suggestions?

Choke seems to be adjusted correctly..


LawnSite Fanatic
Are the plugs black and sooty ?

It's possible there is a issue with the float needle valve in the carb. causing it not to close fully, Worn or trash.


LawnSite Fanatic
The following I would check:

Air filter and pre-cleaner, also the pcv breather tube (there's no pcv valve but the rubber tube serves the same purpose). While you got the air cleaner off, check the choke valve and make sure it's fully open when at Wot.
Fuel filter (might just replace it for gp) and while you got that off and the fuel shut down, carefully remove the bowl from the carb and kinda see if the float isn't stuck. Spark plug's been mentioned.
Either with compressed air or some carb cleaner, clean thoroughly all the throttle linkage crap and springs and stuff.

Beyond that, Kohlers need to idle a full minute after running Wot before you shut them off, so as to cool them down, yes all but the oldest ones backfire if you don't do this.