Abstract: Disclosed herein is a cap for a liquid tank having a filler neck, such as a fuel tank for an outboard motor, which cap includes a hollow body having a top wall portion for closing the filler neck and a depending annular flange for releasably engaging the filler neck. The interior of the tank is vented to the atmosphere through one or more vent ports located in the top wall portion and the vent port(s) is selectively opened and closed by a closure member including a shank threadably mounted on the top wall portion and a cover portion for opening and closing the vent port when the closure member is turned in opposite directions. A dish-shaped baffle disposed inside the cap body in spaced relationship to the top wall portion serves a baffle to minimize spillage of fuel through the vent port(s) and also defines a chamber for collecting fuel which otherwise might leak through the vent port(s) and for draining the collected fuel back into the fuel tank when the motor or tank is in an upright operating position.