You have too much oil in your gas, that's why oil and gas is coming out your exhaust.
Normally this only happens on twin cylinder engines when one of the cylinders is not firing.
The problem I had was oil and gas flowed out the muffler on my snapper 11 hp lawn tractor. To fix it I had to drain the oil and get a new plug. The issue that caused it was I needed a shut off valve in the gas line to stop the gas frome running back into the engine and eventually getting into the oil causing it to gush out the muffler with a lot of smoke. It is an easy fix and it now runs as smooth as new. I hope this helps you
If it is a 2-stroke engine, the oil/gas mixture has too much oil. If it is a 4-stroke engine, the oil sump is overfull.
A gas lawn mower is a lawn mower which is powered by gasoline.
a gas line over the muffler may have broke, or you car is older then 20 year old
If gas is leaking from a Yamaha Razz muffler, then the float may not be set correctly. This means that it is not shutting the intake off.
If the vent is on the top of the cap, it would indicate that something is causing back-pressure inside the tank. Get it serviced.
no
If it is a brand new engine take it back to where you bought it. Because if you do anything to you will void your warranty.
2 examples are Gas analyzer-inserted in muffler Mass airflow machine-inserted in muffler Both measure gas emissions released from a vehicle.
some gas/oil mix (usually lawn boy) some electricity, propane, solar panels, and others just gasoline w/ a separate oil tank.
A free flow muffler can improve mileage but by not by much. It would take a long time to recoup the cost of a new muffler.