What can cause a diesel engine to start but then stall?

A diesel engine starting but then stalling can often be attributed to issues related to fuel supply or air in the fuel lines. Unlike gasoline engines that rely on spark plugs to ignite the fuel-air mixture, diesel engines depend on the compression of air to ignite the diesel fuel. If there is insufficient fuel supply due to a clogged filter, a malfunctioning fuel pump, or presence of air in the fuel lines, the engine may start momentarily but struggle to maintain operation, resulting in stalling.

Moreover, if air has entered the fuel system, it can disrupt the proper fuel delivery to the injectors, leading to a loss of power and causing the engine to stop running after it initially starts. Ensuring a continuous and adequate fuel supply is vital for the vehicle's diesel engine to operate effectively, demonstrating why the correct answer centers on these aspects.

The other options relate to problems typically associated with gasoline engines, or conditions that may not directly cause the stalling after the engine has started. For example, faulty ignition systems or spark plugs are primarily concerns for gasoline engines rather than diesel, while excessive exhaust backpressure or low battery voltage could potentially affect engine performance, they are less directly linked to the phenomenon of starting and then stalling.