Owners of outboard boats have lived with portable fuel tanks for years, but recent efforts to stop gas fumes from escaping by eliminating the two-way vent is causing new concerns.
Without a vent — typically a small screw-type fixture on the tank’s cap or top — a portable tank can swell in the sun, with the internal pressure forcing gas into the outboard, where it can spew into the cowling and dribble out, according to BoatUS.
“These new EPA-compliant portable tanks and jerry jugs have special fittings that greatly reduce evaporative emissions from gasoline,” BoatUS magazine executive editor Mike Vatalaro said. “But where traditional tanks simply vent to the atmosphere, the new tanks won’t vent until the internal pressure reaches 5 psi. In the meantime, fuel could be forced up the fuel line into the outboard, many of which have no means to hold it back.
BoatUS is recommending owners install a fuel-demand valve in the fuel line that will prevent gas from reaching the engine unless it’s called for.
“Leaving the tank disconnected just results in the same gush of gas once you do hook it up, either from the tank end or through the engine,” said Vatalaro. “Installing an inexpensive fuel-demand valve in the fuel line will prevent any gas from reaching the motor unless the motor calls for it.”
BoatUS partnered with the American Boat and Yacht Council for this how-to video.