You can use polyurethane tubing as fuel line as it has exceptional resistance to most gasoline, oils, kerosene, and other petroleum-based chemicals, making PU tubing and hose an ideal choice for fuel lines (although additives in today's gasoline and petroleum products warrant field testing).
The kind of hose you can use for fuel line is rubber fuel line hose that is rated for fuel.
SAE 30R7 hoses are designed for fuel.
Rubber hose that is rated for fuel can be used for return fuel line as well as pressure fuel line.
When using rubber hose for fuel line pressure make sure the rubber hose is rated for the fuel under pressure.
However any fuel hose that is rubber will be okay for fuel return line.
However just note that regular non fuel rated rubber vacuum or heater hose should never be used in fuel applications.
The hose will deteriorate from the inside out and can plug fuel filters and carburetors with rubber debris, long before it springs an external leak.
SAE 30R7 hoses are designed for fuel.
These can go under the hood and are typically used for low-pressure applications like carburetors or a fuel return line.
It can also be used for PCV connections and emissions devices.
SAE 30R9 hoses are designed for high-pressure applications like fuel injection systems.