Tayana -48 Owner's Manual page 29

Fuel Return System
The fuel pump on a diesel engine supplies more fuel than
is actually required for the combustion. The excess fuel is return
to the fuel tank through the fuel return system provided. The fuel
return should always be valve to the same tank from which the
supply is drawn.
CAUTION!
Periodically inspect all connections for leakage and all
tubes for damage. Replace as necessary. Clean the fuel filter
frequently to ensure an adequate supply of clean fuel to the
engine.
DANGER!
Do not drain fuel into the bilge. This could lead to fire, or
explosion.
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