What should be done if water is detected in a fuel system?

When water is detected in a fuel system, it is crucial to remove the water immediately to prevent engine damage. Water can cause significant issues, such as corrosion, poor combustion, and damage to fuel injectors, which can lead to engine performance problems or even failure. Allowing water to remain in the system can result in a range of mechanical failures and costly repairs, as water is not a combustible substance and can disrupt the fuel-to-air ratio necessary for proper engine operation.

In contrast, the other options present inadequate or harmful responses to the presence of water. For instance, letting water evaporate or ignoring low levels does not effectively address the problem, as the water remains in the fuel system until properly drained. Dumping the fuel and refilling might seem like a quick fix, but it does not truly resolve the underlying issue of water contamination, and it can be wasteful and costly. Thus, the appropriate course of action is to immediately remove any detected water to maintain the fuel system's integrity and prevent potential damage to the engine.