What can cause spark plug fouling?

Spark plug fouling can occur due to an improper air-fuel mixture, which means that the ratio of air to fuel being delivered to the engine is not optimal. When the mixture is too rich, there is an excess of fuel in relation to the amount of air. This leads to incomplete combustion, resulting in fuel residue that can accumulate on the spark plug, causing it to foul. A fouled spark plug can lead to misfires, poor engine performance, and difficulty starting the engine.

In contrast, high engine temperatures, correct installation, and the use of high-quality fuel generally contribute to optimal engine performance. High temperatures usually indicate efficient combustion, while correct installation ensures the spark plug functions as designed. Using high-quality fuel helps maintain a cleaner combustion process, reducing the likelihood of fouling and promoting better engine operation. Therefore, the condition described in the selected choice directly points to one of the primary causes of spark plug fouling.