If the pump is running, but no fuel is delivered, what should be your first diagnostic step?

The first diagnostic step when a pump is running but no fuel is being delivered should focus on understanding the system's design and layout. Reviewing the as-built drawing provides critical information about the configuration of pipes, valves, and system components. This initial step helps to identify any potential issues in the layout that could affect fuel delivery, such as closed valves or blocked passages that may not be apparent just by inspecting the pump or valves directly.

Understanding the construction and arrangement of the entire system enables you to pinpoint where the problem might be occurring and ensures you don’t overlook critical components that may not be situated directly next to the pump. Without this foundational knowledge from the drawings, troubleshooting can become inefficient and may lead to unnecessary checks that do not address the underlying issue.