Fuel circuit system

The system has an advance (2) and a return pipe (4) arranged between an internal-combustion engine (3) and a fuel tank (5) of a motor vehicle. The return pipe is provided within the fuel tank and outlets (8), such that in the fuel tank a running line (7) is provided, which extends over a substantial part of the length of the fuel tank. The line horizontally in the fuel tank. The return pipe in driving direction, is arranged within the fuel tank.