Jet Pump

The jet pump utilizes the velocity of fuel returning from the engine to produce negative pressure in it.
Using the pumping effect produced by the negative pressure, the jet pump transfer fuel from the sub-compartment to the main compartment of the fuel tank.
When the return line nozzle is clogged, the fuel sent back through the return line flows back into the fuel tank via the relief valve.

Fig 1: Identifying Jet Pump Return Line & Component
Courtesy of SUBARU OF AMERICA, INC.