Join Date: Oct 2011
Thanked 33 Times in 27 Posts
Rep Power: 68
Could be a problem with the choke/choke cable/dirty fuel filter/faulty fuel tank valve/poor connection from carb to motor/plugged air filter.
The fuel air mixture is off, if it isn't outside the carb it's in it. Back firering is a lean condition, but a rich condition will cause the motor to rev when the fuel is running out. You may have been running rich and are now experiencing a problem causing a lean condition, 2 problems.