An evap leaks smoke tester indicator needle is at the top of the flow gauge, what could this indicated?

When the smoke tester indicator needle is at the top of the flow gauge, it indicates a large leak in the evaporative (evap) system. In an evaporative emissions system, the purpose of a smoke test is to identify any leaks that might allow fuel vapors to escape into the atmosphere. A needle position at the top of the gauge suggests that there is a significant amount of airflow or smoke escaping, which correlates with a large volume of leakage. This is critical for diagnosing issues because large leaks can significantly affect the vehicle's emission control system and overall performance.

In contrast, if there were no leak or a smaller leak, the needle would not move to the top of the gauge. Understanding the difference in readings helps technicians accurately diagnose and fix issues with the evap system, ensuring compliance with environmental regulations and optimal engine performance.