If the fuel discharge valve fails to open, what should you check first?

When troubleshooting a fuel discharge valve that fails to open, the first step is to check for water in the filter separator sump. Water accumulation can indicate a problem with the fuel system, potentially causing the discharge valve to fail due to contamination. If water is present, it may have affected the fuel's properties or may have blocked fuel flow, preventing the valve from opening as required.

By starting with an examination of the filter separator sump, you address a key factor that can impact the entire fuel system's performance. Identifying and resolving water issues early helps prevent further complications and ensures a more thorough approach to troubleshooting. This foundational step is crucial because water in the fuel can lead to more significant operational issues and system failures if not addressed promptly.