My friend's brother in law's lawn tractor won't start and I'm trying to help him with it. 
 
It has spark; about 3/16" worth of spark on a spark checker.
 
It has a 15003 7042 carburetor, that we found had a deformed float needle; we replaced it.
The float moves freely.
The fuel pump appears to work.
The electric fuel cut off (in the bottom of the float bowl) works.
 
The engine will fire when starting fluid is sprayed into the carburetor.
 
The engine has 85-90 pounds of compression when cranking.
 
We will remove the carburetor, again, and clean it in my ultrasonic cleaner next.
 
Can anyone think of something we are overlooking?
 
Also, this is an air cooled engine, but the oil looks like chocolate milk. Weird huh!
 
Thanks,
 
Bill

Sounds like a jet in the carb is clogged. 
 
A full tear down and check of all orifices/ jets is due.
 
 
.

nashville_bill
My friend's brother in law's lawn tractor won't start and I'm trying to help him with it. 
 
It has spark; about 3/16" worth of spark on a spark checker.
 
It has a 15003 7042 carburetor, that we found had a deformed float needle; we replaced it.
The float moves freely.
The fuel pump appears to work.
The electric fuel cut off (in the bottom of the float bowl) works.
 
The engine will fire when starting fluid is sprayed into the carburetor.
 
The engine has 85-90 pounds of compression when cranking.
 
We will remove the carburetor, again, and clean it in my ultrasonic cleaner next.
 
Can anyone think of something we are overlooking?
 
Also, this is an air cooled engine, but the oil looks like chocolate milk. Weird huh!
 
Thanks,
 
Bill
 
Here the info you need:
when you spray carb cleaner does it stay running. Also 3/16 of the spark tester is not enough spark it has to be bright red or 100%  usually indicates that coolant has mixed with the engine oil, most likely due to a faulty head gasket, which means water from the cooling system is leaking into the combustion chamber and then into the oil pan, causing the milky brown appearance; this is a serious issue that requires immediate attention from a mechanic to repair the head gasket. 

 
  A small gasoline engine typically needs 140–160 pounds per square inch (PSI) of compression to start. ok make a note of this. thanks Tom's Small Engines

QuoteReply

when you spray carb cleaner does it stay running. Also 3/16 of the spark tester is not enough spark it has to be bright red or 100%  usually indicates that coolant has mixed with the engine oil, most likely due to a faulty head gasket, which means water from the cooling system is leaking into the combustion chamber and then into the oil pan, causing the milky brown appearance; this is a serious issue that requires immediate attention from a mechanic to repair the head gasket. 

 
  A small gasoline engine typically needs 140–160 pounds per square inch (PSI) of compression to start. ok make a note of this Thanks Tom's Small Engine

It's an air cooled engine, no coolant to mix/leak.
 
Also, he said it fires off with starting fluid.  (IME, a fueling issue)
 
.

He is going to remove the carb and I'll dismantle and clean in my ultrasonic tank. Thanks for the helpful answer.
 
Bill

Please post back how it goes...
 
.