Fuel Delivery System - Mercury MerCruiser Product Applications Manual

Fuel Delivery System

Lubricant, Sealant, Adhesives
Tube Ref No.
Fuel Delivery System
Always adhere to all applicable Marine Regulations (United States Coast Guard [USCG],
European Union ‑ Recreational Craft Directive [EU‑RCD], and so on) and the standards
they reference (American Boat and Yacht Council [ABYC], Society of Automotive
Engineers [SAE], International Standards Organization [ISO], and so on) when installing
the fuel delivery system.
The primary concern in designing the fuel system should be safety. This must be
accomplished with a technically sound design and appropriate maintenance procedures.
Also, design the fuel delivery system to deliver the fuel to the engine minimizing fuel
restriction and at the lowest temperature. Gasoline is extremely sensitive to vaporizing if
placed under a vacuum (low pressure) and exposed to moderate or high temperatures.
This is particularly true if winter blend fuels with a high Reid vapor pressure (RVP) are
encountered in warmer temperature areas. Excessive restriction in the fuel delivery system
may cause a condition known as vapor locking. This typically occurs after the engine has
been operated at high RPM and then shut off and allowed to sit for 15 minutes to 2 hours.
During this time, the engine heat soaks causing the temperature of the fuel system to
increase. Upon restart, the combination of heat and vacuum in the fuel system causes the
fuel to vaporize. The fuel system cannot handle this vapor, and therefore, fuel starvation
results when the boater attempts to resume operation. Depending upon the degree of vapor
locking, this can range from a hesitation or bog when accelerating to a complete stalling
of the engine. To minimize the potential for this problem, observe the guidelines to limit
fuel delivery restriction to 6.9 kPa (1 psi) vacuum or less and fuel inlet temperature to
44 °C (110 °F) or less.
The fuel delivery system is an integral part of the boat. Mercury MerCruiser makes no
attempt in this manual to cover all aspects of design and integration of the fuel delivery
system due to the broad range of possible configurations and the numerous regulations
and standards that cover this area. Observe the applicable standards and regulations for
the markets where your product will be sold, along with any information from the fuel system
component manufactures. The following general guidelines are provided.
Avoid serious injury or death and property damage due to improper boat design and
construction. Always adhere to all applicable Marine Regulations (United States Coast
Guard [USCG], European Union ‑ Recreational Craft Directive [EU‑RCD], and so on) and
the standards they reference (American Boat and Yacht Council [ABYC], Society of
Automotive Engineers [SAE], International Standards Organization [ISO], and so on)
when designing and constructing the boat and the boat components, such as the engine
compartment, fuel delivery system and exhaust system.
Safety is the main concern in the design of a boat's fuel system; this must be achieved
through a technically sound installation and constant inspection.
The fuel system, from the filler pipe to the fuel pump, is the same in principle for all boats.
Page 5A-2
Loctite 567 PST Pipe Sealant
9
Description
WARNING
!
WARNING
!
Where Used
Fuel inlet connection
90-863758060 AUGUST 2006
Part No.
92-809822