When a fuel injection nozzle overheats, which of the following can be expected?

When a fuel injection nozzle overheats, one of the most likely outcomes is that the fuel metering will vary. This occurs because excessive heat can affect the viscosity of the fuel and potentially cause thermal expansion of the nozzle components. When the fuel injector fails to operate correctly due to overheating, it may not deliver the precise amount of fuel needed for optimal combustion in the engine. This can lead to an inconsistent fuel-air mixture, directly impacting engine performance, efficiency, and emissions.

While variations in fuel metering are critical, other outcomes such as explosion of the fuel or immediate engine shutdown are less likely in this scenario. Fuel injectors and the engines they serve are designed to handle high temperatures, and while overheating can lead to various issues, outright explosions or catastrophic failures like a cracked cylinder head are typically the result of more severe systemic failures or critical malfunctions. Hence, the variation in fuel metering remains the most direct and relevant consequence of an overheated fuel injection nozzle.