Which fuel system operates at a pressure of 3-5 PSI?

The low pressure carbureted system operates at a pressure of 3-5 PSI, which is characteristic of its design. In this system, fuel is delivered to the engine via a carburetor, which mixes air and fuel at low pressures to create the optimal combustion mixture for the engine. This low pressure is sufficient for the carburetor to function effectively, allowing for the appropriate atomization of the fuel.

Understanding the context of the other fuel systems helps clarify why they operate at different pressures. High pressure fuel injection systems, for example, operate at significantly higher pressures—often 30 PSI or more—to ensure an efficient fuel atomization necessary for modern engines. Diesel fuel systems also operate at higher pressures than a low-pressure carbureted system, typically requiring pressures that can exceed 100 PSI for effective injection into combustion chambers. Gasoline vapor systems operate on different principles related to vapor recovery and typically do not maintain fuel at the designated low pressure range of 3-5 PSI. Therefore, the low pressure carbureted system is the correct choice for operating within the specified pressure range.