Small Engine Troubleshooting Problems? Ask a Mechanic Now.
What is the model and type of engine?
May be a dumb question, but what is oil level at?
Have you check that the breather passage is clear. May need to replace. This is the biggest issue I have with them blowing back through the carb.
possible that the reed is bad and not working properly. This will cause blowback through carb like you are referring to
crankcase breather. Has a reed inside it. . one way check valve. will allow oil to flow out to carb if it is not working properly
can also be caused by a loose oil cap or oil cap not sealing, but RARE!
Consist of part numbers:
Briggs and Stratton 697124
Briggs and Stratton 794682
Briggs and Stratton 794683
you also have a gasket and 2 screws included.
If the hose is split or cracked, it can cause this problem you are having.
If the reed is not opening and closing properly, it will cause this problem.
Pull the breather hose, from your intake, and see where the oil comes from.