The first engine component of an engine which is dependent on the kind of engine and fuel used in an internal combustion engine is the ignition system. A precisely timed spark would ignite petrol engines, while it is through compression heating that would ignite diesel engines.
With a controlled and precise of a mixture of an electric spark from a spark plug, the mixture would create an ignition in a spark ignition engine. Note that almost all engines in gasoline are of this kind, while diesel engines timing is controlled in a precise manner by the injector and pressure pump.
Ignition happens when the temperature of the fuel/air mixture is taken over by the autoignition temperature because there is heat generated during the compression stroke of which air is compressed. Diesels composed the vast majority of compression ignition and this is because fuel is mixed with the air once the air has reached ignition temperature.
Note that fuels burn faster and more efficiently when there is a large representation of surface area to the oxygen in air. The traditional way to atomize liquid fuels, which is needed to create a fuel air mixture, is to have it done with a carburetor in petrol engines and with the fuel injection in diesel engines. The modern petrol engines nowadays use fuel injection too although there is a difference in the technology.
In order to supply fuel into the cylinder, the use of carburetor is used in simpler reciprocating engines. In terms of cost and flexibility, carburetor technology lost to fuel injection in the mid 1980s, although it has reached a top level of precision and sophistication. Small engines though still remain to use the simple forms of carburetor, like lawn mowers and the more sophisticated forms of engines used in small motorcycles.
Fuel injection systems have been used mostly by automobiles with larger gasoline engines. The timing of the injection initiates and controls the combustion, and this is why diesel engines have always used fuel injection system.
In the case of autogas engines, it uses either fuel injection systems or open or closed loop carburetors.
A fuel pump is what most internal combustion engines require. As for diesel engines, an all mechanical precision pump system is used which delivers a timed injection into the combustion chamber, and thus, in order to overcome the pressure of the combustion chamber, there should be a time injection directed into the combustion chamber.
For four stroke engine, it has these parts of the engine, namely the crankshaft, connecting rod, one or more camshafts and valves.