Which factor can negatively impact fuel combustion in engines?

The presence of water or impurities in fuel can significantly disrupt the fuel combustion process in engines. Water, when present in fuel, leads to incomplete combustion, which in turn can cause issues such as misfiring, loss of power, and even damage to engine components. Impurities, which can include dirt, rust, and other foreign substances, can clog filters and injectors, limiting fuel flow and further exacerbating combustion problems. This contamination reduces the fuel's overall efficiency and may result in increased emissions and operational instability.

In contrast, factors such as the correct fuel-to-air ratio, high-quality fuel additives, and proper fuel storage practices improve combustion efficiency and engine performance. These elements work together to ensure that fuel combusts effectively, thereby maximizing energy output and maintaining engine health.