The ornamental design for a fueltank, as shown and described.
FIG. 1 is a rear, bottom, left perspective view of a fuel tank showing the new design in an environment of use, where the surrounding machine is not claimed;
FIG. 2 is a rear, bottom, right perspective view thereof;
FIG. 3 is a rear, top, left, perspective view thereof;
FIG. 4 is a left-side elevation view thereof;
FIG. 5 is a right-side elevation view thereof; and,
FIG. 6 is a rear elevation view thereof.
The broken lines of even length shown in the drawings illustrate environmental subject matter and form no part of the claimed design. Inventive aspects of the current design exist in the fuel tank as a whole as well as in the portions of the fuel tank that are only visible when installed, as shown in FIGS. 1-6.