Fuel Demand Valve (Fdv) Requirement; Mercury Marine's Pressurized Portable Fuel Tank - Mercury 150 FourStroke Operation & Installation Manual

Fuel Demand Valve (FDV) Requirement

Whenever a pressurized fuel tank is used, a fuel demand valve is required to
be installed in the fuel hose between the fuel tank and the engine. The fuel
demand valve prevents pressurized fuel from entering the engine and causing
a fuel system overflow or possible fuel spillage.
The fuel demand valve has a manual release. The manual release can be used
(pushed in) to open (bypass) the valve in case of a fuel blockage in the valve.
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Mercury Marine's Pressurized Portable Fuel Tank

Mercury Marine has created a new portable pressurized fuel tank that meets
the preceding EPA requirements. These fuel tanks are available as an
accessory or are provided with certain portable outboard models.
SPECIAL FEATURES OF THE PORTABLE FUEL TANK
• The fuel tank has a two‑way valve which allows air to enter the tank as
the fuel is drawn to the engine, and also opens to vent to the atmosphere
if internal pressure in the tank exceeds 34.4 kPa (5.0 psi). A hissing noise
may be heard as the tank vents to the atmosphere. This is normal.
• The fuel tank includes a fuel demand valve that prevents pressurized fuel
from entering the engine and causing a fuel system overflow or possible
fuel spillage.
• When installing the fuel tank cap, turn the cap to the right until you hear a
click. This signals that the fuel cap is fully seated. A built‑in device
prevents overtightening.
• The fuel tank has a manual vent screw which should be closed for
transportation and open for operation and cap removal.
Since sealed fuel tanks are not vented, they will expand and contract as the
fuel expands and contracts during heating and cooling cycles of the outside air.
This is normal.
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FUEL AND OIL
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Fuel demand valve ‑ installed in the
fuel hose between the fuel tank and
the engine
Manual release
Vent/water drain holes