How is diesel engine fuel delivered to the combustion chamber?

• A. Admitted to cylinder during intake stroke
• B. Mechanically atomized by high pressure
• C. Mixed with air in the intake manifold
• D. Fed to the carburetor under pressure

Answer: (B)

Diesel engines deliver fuel by injecting it directly into the combustion chamber at very high pressure, atomizing it into fine droplets as it is sprayed. The air is drawn in and compressed to a high temperature, and the injected fuel auto-ignites when it contacts this hot air. This direct, high-pressure injection is what allows diesel engines to achieve efficient combustion and proper timing without a spark plug.

Fuel isn’t admitted during the intake stroke, nor is it mixed with air in a manifold before entering the cylinder, and diesel engines don’t use a carburetor.