Why is a carburetor not used in diesel engines?
All diesel engine use fuel injection and they always have done. Diesel does not evaporate like petrol does so a carburetor cannot be used and the fuel has to be injected into the intake air under very high pressure in order to get it to atomise. ... The intake valve(s) close, and the compression stroke begins.
Diesels are compression combustion engines, they need to take in a full charge of air regardless of the engine speed and load. The fuel is not mixed with air by carburetors as with gasoline engines, rather it is injected directly into the cylinders at the appropriate time when combustion needs to take place. There is also no butterfly valve on diesels, the throttle controls how much fuel is injected rather than the total amount of air-fuel mixture as with gasoline engines.