What is a lean air/fuel mixture?

A lean air/fuel mixture is characterized by having too little fuel relative to the amount of air present in the mixture. In the context of combustion engines, the ideal mixture is a balanced one, where the ratio of air to fuel is optimized to ensure complete combustion. However, in a lean mixture, the shortage of fuel means that there may not be enough combustible material to mix with the available air, which can lead to incomplete combustion and various performance issues.

This condition can result in higher engine temperatures and can create knocking or pre-ignition, which is detrimental to engine health. Consequently, a lean mixture can affect power output and efficiency, making it crucial for small engine systems to maintain the right balance of air and fuel for optimal performance. Understanding this concept is essential for diagnosing fuel delivery problems and ensuring that the engine operates effectively.