TPD 1399E Chapter 6
Page 17
Fuel systems
In some applications there will be legislation covering
the design of fuel systems. The details in this section
are generally regarded as good practice, however, and
may be used in the absence of a specic legislative
directive.
Note: Many of the marine engine problems
encountered at sea are due to design and assembly
faults in the fuel system. A good system is not hard
to achieve, and avoiding the pitfalls described in
this section will go far towards achieving reliability in
service.
Fuel connections
The M65 engine has connections for a fuel feed from
the tank at the fuel lift pump (A2) and a fuel return to
the tank from the fuel lter head (A1).
Fuel connections on the engine
Fuel feed
1/2” UNS female for
5/16” OD pipe
Fuel return
7/16” UNS male for 1/4”
OD pipe
It is recommended that the exible fuel pipes available
as an option with the engine are specied. These
provide connections as shown below.
Optional exible fuel pipes
Fuel feed
The free end has a 1/4”
BSP nut and olive to suit
5/16” OD pipe (to be
supplied by installer)
Fuel return
The free end has a 1/4”
BSP nut and olive to
suit 1/4” OD pipe (to be
supplied by installer)
Note: A common reason for service problems with
fuel systems is the use of poor or incompatible
connectors.
Flexible hoses should be used with purpose made
end ttings, and should not be secured to a plain pipe
with hose clamps.
Where adaptors are necessary to connect components
with different thread sizes, sealing should be achieved,
where possible, by the use of a thread sealant on
tapered threads.
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