Fouled Spark Plugs

Q: My mechanic told me that my spark plugs might be fouled. What does this mean and how does a spark plug get fouled?

A: A fouled spark plug has been coated with excessive oil, fuel, or other by-products of combustion such as carbon. These deposits coat the insulator tip of the spark plug. When this happens, the insulator part now acts as a conductor of electricity and will short out the electrical spark. Your engine could have several plugs fouled or just one. Depending on the extent and the number fouled, bad spark plugs can cause the engine to lose power, run rough, overheat, and even not run at all.