The system has a pump with connected feed pipe containing a fuel filter. The feed pipe (4) has a by-pass pipe (9) leading past the filter (7). It also has components to open and close the by-pass after a set use period or condition of the filter. The components are contained in the fuel tank (1), and consist of e.g. a reversing valve. The valve is operated after a set time period or after a pre-selected mileage traveled. The by-pass contains a second fuel filter.
