Fuel System; Fuel Delivery System; Anti-Siphon Valve; Fuel Supply Module (Fsm) - Mercury MerCruiser Service Manual

MPI ECT Fuel System

Fuel System

Fuel Delivery System

Failure to comply with the required boating standards can result in serious injury or death. Always adhere to all applicable
Marine Regulations (United States Coast Guard [USCG], European Union ‑ Recreational Craft Directive [EU‑RCD], etc.) and
the standards they reference (American Boat and Yacht Council [ABYC], Society of Automotive Engineers [SAE],
International Standards Organization [ISO], etc.) when installing the fuel delivery system.
IMPORTANT: Refer to boating standards (NMMA, ABYC, etc.) and Coast Guard regulations for complete guidelines.
• An anti‑siphon valve is required by the US Coast Guard.
• All spark‑ignition marine inboard and sterndrive engines sold in California must use low permeation fuel supply and return
lines to comply with applicable California Air Resources Board regulatory standards. Low permeation fuel line 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.
• Flexible fuel line must be used to connect fuel line to engine to absorb deflection when engine is running.
• Fuel lines and fittings must be Coast Guard approved (USCG type A1), and not be smaller than 10 mm (3/8 in.) I.D.
• Multiple engine installations: It is best to use a fuel pickup and supply line for each engine. If a single pickup and supply
line is used, fittings and line must not be smaller than 13 mm (1/2 in.) I.D.
• Larger diameter (than previously specified) lines and fittings must be used on installations requiring long lines or numerous
fittings.
• The tank breather pipe must have an inner diameter of at least 13 mm (1/2 in.) and must be fitted with a swan neck to
prevent water from entering the tank.
• The filler pipe outer diameter should be at least 50 mm (2 in.).
• All connections should be on the upper side of the tank.
• A drain plug at the lowest point on the tank will permit removal of water and sediment.
• Establish the exact route and length of the fuel lines at the first installation of the engine to prevent problems later in
connecting them to the engine.
• To prevent chafing, holes where the lines run through the bulkheads should be rounded off or protected with rubber
grommets and fuel lines must be well secured.
• The fuel pickup should be at least 25 mm (1 in.) from the fuel tank bottom to prevent picking up impurities.
• The maximum measured vacuum at the engine's fuel inlet must not exceed 2 in. Hg or 6.9 kPa (1 psi) at idle, 3000 RPM,
and full throttle RPM.
Special Information About Electric Fuel Pumps
IMPORTANT: The electric fuel pump and factory installed water‑separating fuel filter have been carefully designed to function
properly together. Do not install additional water‑separating fuel filters between the fuel tank and the engine. Use the Mercury
in‑line fuel filter with the boost pump.
The installation of additional filters may cause:
• Vapor lock
• Difficult warm‑starting
• Piston detonation due to lean fuel mixture
• Poor driveability
Anti‑Siphon Valve
U.S. boating standards and regulations specify that an anti‑siphon valve be used on any application where any portion of the
fuel line falls below the top of the fuel tank. This valve serves to minimize the amount of fuel that could leak into the bilge of the
boat in the event of a fuel system leak. A mechanical anti‑siphon valve or an electrically operated fuel shut off valve is
acceptable for this purpose and should be installed in accordance with industry standards and the manufacturer's instructions.
The mechanical valve must be carefully sized to the fuel pressure head produced in a given application (a function of the fuel
level height between the lowest and highest point in the system). The valve must check the flow of fuel when the engine is not
running, yet avoid excessive restriction when the engine is operating. An overall fuel system pressure drop of 6.9 kPa (1 psi) or
less is desirable but may not be achievable in all cases.

Fuel Supply Module (FSM)

FSM Removal

1.
Release the fuel pressure on the fuel rail. Refer to Fuel Rail Removal.
Page 5A-10
WARNING
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© 2016 Mercury Marine 90-8M0099748 eng DECEMBER 2015