Its use helps ensure that fuel overflow will not damage your deck or pollute the water. Instead, excess fuel is caught inside the 0.6 gallon reservoir. Excess fuel drains from the bottom of the reservoir back to the fuel tank. This drain connection also serves as the required tank vent. A breather line is installed from the top of the reservoir to the outside. An optional diesel odor filter may be installed in this line.
Models 3816 & 5116 have a 2-stage connection for 1-1/2" or for 2" fuel fill hose