These two types of pollution from unburned fuel are aggravated by hot outdoor temperatures.

This results in lost power, high emissions, and unburned fuel.

This leads to unburned fuel out the exhaust and a characteristic trail of black smoke.

Those engines use a small amount of unburned fuel as lubricant and then expel it.

The unburned fuel also passes through the catalytic converter, which it can damage.

Back burning operations were conducted to remove unburned fuel and direct the fire.

The air around the field shimmered as unburned fuel floated through the air.

Rich mixtures are bad because the unburned fuel creates pollution.

This unburned fuel and oil help keep the engine cool.

This results in unburned fuel escaping through the exhaust system and into the environment.