Diesel Fuel Systems Menu Sub Menu Summary Basic Principles Diesel Fuel Injection Diesel engines draw air only, past the intake valve into the cylinder.
Fuel is injected into the cylinder at high pressure.
The amount of fuel injected varies to suit load, and control engine speed. For all diesel engines, at a fixed fuel setting, the amount of fuel delivered to the engine will increase as engine and pump speed increases. It must be controlled, or over-speeding of the engine will occur. The cetane rating of a diesel fuel defines how easily the fuel will ignite when it is injected into the cylinder. The lower a fuel's cetane rating, the longer it takes to reach ignition point.