Are you looking at a device under the hood or under the car near the fuel pump?

The pressure reg is under the hood , fuel accumulator under car.

The pressure reg should have a vacuum line , fuel return.

Accumulator has fuel in / out then a vent hose that leads to the suction side of the fuel pump. This was done so if the diaphragm tears, fuel circulates back to the tank rather than being dumped on the ground / hot exhaust like some cars.