Fuel Lines And Fittings; Fuel Inlet Connection - Mercury MerCruiser Product Applications Manual

Fuel Lines and Fittings

• U.S. boating standards and regulations specify the sole use of USCG Type A1 fuel
lines in the engine compartment or in any location in the boat where a break in the line
could result in a discharge of 150 cc (5 oz.) of fuel in 2½ minutes.
• To meet 2007 California Air Resources Board regulations, any boat manufactured for
sale, sold or offered for sale in California, or that is introduced, delivered or imported
into California for introduction into commerce must use low Permeation Fuel Hose from
the primary connection of the fuel tank to engine.
• Low permeation fuel hose is defined as not exceeding 15 g/m²/24 h with CE10 fuel at
23° C as specified in SAE J 1527—Marine Fuel Hoses. For more information refer to
Section 1A - California Regulations for 2007—Low Permeation Fuel Hose
• The minimum fuel line and fitting sizes should be used. Larger sizes may be required
on applications with longer fuel lines or numerous fittings.
Description
Minimum fuel line diameter on single‑engine gasoline
installations
Minimum fuel line diameter on multi‑engine gasoline
installations
• On Multi-Engine Gasoline Installations: Use a fuel pickup and fuel tank supply line
for each engine. If a single pickup and fuel tank supply line is used, the line must be
13 mm (½ in.) ID or larger.
• In addition to increasing restriction, long fuel line lengths and the use of numerous
fittings can increase the fuel inlet temperature to the engine by absorbing heat from the
engine compartment. Use the Fuel System Pressure and Temperature Test to
determine if fuel pressure and temperature are within an acceptable range. If
temperature is excessive, it will be necessary to reduce the fuel line length and/or the
number of fittings or to insulate the components.
• Fuel lines should be routed as low as possible in the engine compartment to keep them
in the coolest region. Temperature increases significantly with increased engine
compartment height.
• The slope of the fuel line should be kept as consistent as possible to avoid high spots
that can trap vapor and contribute to vapor locking problems.
• Holes where the lines run through the bulkheads should be carefully rounded off or
protected with grommets to prevent damage from vibration and chafing.
• The fuel line should be installed free of stress and firmly secured to prevent vibration
and/or chafing. Clamps used to secure the line should not pinch or kink the line.
• Sharp bends in the fuel line should be avoided.
• A flexible fuel line must be used to connect the fuel supply line to the fuel inlet fitting
on the engine to absorb deflection between the engine and the hull structure when the
engine is running.
IMPORTANT: If the engine is equipped with a boost pump, an inline filter must be installed
between the fuel tank and the boost pump. This filter is provided with the engine package.

Fuel Inlet Connection

Connect the flexible hose of the fuel delivery system to the locations shown using
appropriate industry approved fittings and hardware. Required fitting sizes are listed below.
90-863758060 AUGUST 2006
Fuel Inlet Fitting Sizes
Fuel Delivery System
Specification
10 mm (3/8 in.)
13 mm (½ in.) ID or larger
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