Surging Lawn Mower

I have an older Craftsman GT 5000 lawn tractor and it seems like I have to work on it every time I mow the grass.  Here recently the RPMs surge constantly and it will not idle.  I decided to figure out what was wrong with it this morning. 

After thinking about what it was doing I come to the conclusion that it must be starving for fuel.  So the first thing I check was the fuel lines and filter.  I had two separate places where the fuel line was leaking and the filter was also in need of replacement. 

After replacing the bad fuel line and filter I found the surging of the RPM was not as severe, but still bad enough to continue troubleshooting.  I reluctantly pulled the air intake and carburetor off to check for possible issues. 

I removed the bowl under the carburetor and there I found my problem.  The bowl had actually rusted on the inside due to water sitting at the bottom of the fuel bowl.  This particular engine has a fitting at the bottom of the fuel bowl where it sucks fuel in for the carburetor.  That fitting has a small hole that will only allow a certain amount of fuel to enter the carburetor at a time.  That little orifice was clogged with rust. 

I cleaned up the carburetor and blew it out with air then reinstalled everything.  No more surging and I could idle the engine again.  Wahoo!! Time to mow some grass.