Normally from an engine backfire. The plug fires when the intake valve is partially open which will explode the fuel in the intake and carb.
ok i have a 1986 jeep cherokee it wont start from the key in side it turns over but dosent fire up an its got (gas an fire) it will start if you pull start it an it has a carb
carburetor
Check ignition timing Timing chain "jumped"?
A carburetor will not start when it does not yet enough fuel. A carburetor will not start if it gets too much. Fuel and not enough air.
A misfire will cause flames to come out of the carburettor
Check the muffler for obstructions. Dirt dobbers and other insects love to make nest in the outlet holes.
Carburetor
The carburetor needs rebuilding.
Timing is backwards turn distributor 180*
No you can't start it on fire but you can start fire with it! at least i think...
if it has a carburetor it is normal
The fuel is not getting from the tank to the carburetor.