What causes a 1993 Honda Prelude to run rich?

A 1993 Honda Prelude may run rich due to several factors, including a malfunctioning fuel pressure regulator, a faulty oxygen sensor, or a dirty air filter that restricts airflow. Additionally, issues with the engine control unit (ECU) or fuel injectors can lead to excessive fuel delivery. Vacuum leaks can also disrupt the air-fuel mixture, contributing to a rich condition. Regular maintenance and diagnostics are essential to identify and resolve these issues.