Small Engines (Lawn Mowers, etc.): B&S motor help, gunk, bottom side

Question
I have a B&S Model #422707 motor on MTD Tractor.
Motor will start, but onlys runs with choke fully on.
Doesn't run at full speed either.


Answer
Likely the carb is full of water and gunk.  On the bottom side of the carb is a nut that takes a 5/8 wrench, remove it, and fuel should dribble out, crank the engine some and more fuel and gunk should pulse out, if not, then there is a problem before the carb.
MTD was known for using crappy fuel lines that would crack and leak
well before the short Briggs line would, so you might take a peek
from the filter to the tank.

If all there is good, and you get fuel out when cranking, then get a
3/16 allen head wrench and stick in that hole and remove that jet that is threaded in there and clean it out.  While it is out, crank the engine a little more, and with luck, more crud and water will get pushed out the carb, reassemble, and see how it runs.

Let me know.

Fish