As opposed to electronic things – more specifically, computer controlled things – whose workings are opaque and which generally cannot be fixed but rather tossed and replaced.

Carburetors – which are mechanical fuel-delivery systems – are also self-contained things. Put another way, there are no peripheral things – other than a fuel pump (usually also mechanical).

Behold, as an example, the carburetor that feeds air and fuel to the 455 cubic inch (that's about 7.5 liters for you Millennials and Gen Zs, who had the bad luck to be born after the metric system ruined what had been the much more personal and so interesting conveyance of engine displacement via size, which used to matter) V8 that lies under the hood of the Orange Barchetta, my '76 Pontiac Trans-Am.

What you see is all there is.

Literally.

The carb perched on top of the 455 is the fuel system. Yes, there is also a gas tank and a fuel pump – but these merely store/deliver the fuel to the carburetor. The carburetor is a self-contained system.