For my Lawn tractor i just unscrewed the gas cap a bit and shook the rider back and forth with my hip. I had to replace my gas cap because the breathing function of it had worn out.
Husqvarna
A person can get an owner's manual for a Craftsman lawn tractor by contacting the Craftsman company. The phone for customer service is 1-888-331-4569.
1997
The pastic case on left side of motor. Unscrew nut, remove cover. Unscrew the second nut. You have it.
MTD
1997
2006
Try searspartsdirect.com
it should be under the seat.
March 01 2004
Gates
The float valve in the carburetor is not working properly. You will need to remove the carburetor and clean it or replace it.