Small Engines (Lawn Mowers, etc.): B&S engine knocking at shutdown, murray riding mower, float bowl

Question
I am having a couple of problems with my Murray Riding Mower; the engine is a B&S model 42A707-2653-E1 (Code 9710315A)), 17.5HP Twin II I/C.

Problem1:  When I tune off the engine and it is whining down I hear a knocking sound. It dose not knock when I start it or when running.

Problem 2: To start the engine and to keep it running I must pull the chock full out and keep it there.

Answer
Wayne

What you need to check is the fuel solenoid  this is on the bottom of the carb attached to the float bowl. What that does is shut your fuel supply off as soon as you turn the key,sometimes they call it a anti backfiring switch to prevent fuel dumping in the carb causing knocking noise ,
backfiring and flooding the carb.the reason the choke has to be pulled out is because it is starving for fuel and what you are doing is forcing the choke to push more fuel. It is time for a carburetor rebuild or buy a new one