What are the symptoms of a bad fuel injector?

A faulty fuel injector creates a number of different issues on an engine, including stalling, lower than average fuel economy, a vibrating engine, a rough idle or running too rich. Faulty injectors are tricky to diagnose because many of their symptoms mimic more common problems, such as a vacuum leak or bad spark plug.

One of the most common traits of a bad fuel injector is when it fails to fire. This results in the engine running too lean. The check engine light in the vehicle usually illuminates to notify the driver of the issue. When an engine runs too lean it may stall.