What unit must be adjusted to change fuel pressure warning limits?

The fuel pressure warning limits are primarily determined by the pressure-sensitive mechanism integrated into the aircraft's fuel system monitoring. This mechanism is designed to detect deviations in fuel pressure and activate warning signals if the pressure falls outside predetermined safe limits. By adjusting this mechanism, technicians can set the threshold at which warnings are triggered, ensuring that any abnormalities in fuel pressure are promptly identified and addressed.

The pressure gauge, while an essential tool for monitoring fuel pressure, does not directly adjust the warning limits; it simply provides a visual indication of the current pressure. Similarly, a ballast does not play a role in adjusting fuel pressure limits; it primarily serves to stabilize weight distribution in the aircraft. An electrical resistor may impact electrical circuits in some way but does not alter the warning limits related to fuel pressure. Therefore, the pressure-sensitive mechanism is the correct unit to adjust for changing the fuel pressure warning limits effectively.