Deck Fill Protection Device
Manufactured by Marsh Marine...Tank Cleaning Professionals
“Our experience is your protection since 1966”
Diesel Fuel...Continued:
A
ir
will
enter
a
tank
only
when
its
fuel
level
diminishes,
i.e.
you
are
using
or
draining
fuel,
or
the
fuel
is
contracting
due
to
cooling.
Since
it
is
heating
up,
expanding,
air
will
be
vented
out,
not
into
the
tank.
Precise
studies
have
shown
that
even
with
the
air
entering
a
tank
that
is
100%
saturated,
the
amount
of
condensation
it
might
deposit
on
the
tank
walls,
if
the
tank
were
indeed
cooler
than
the
outside
air,
is
too
small
to
ever
become
a problem.
There simply is not enough volume exchange to make much difference. If you are finding water in your tanks
or fuel bowls, believe me it isn’t from condensation. It got there from bad fuel you took aboard, a leaking fuel
cap, a leaking fuel level sender, or an improperly installed fuel vent. Never take for granted that fuel received
from a marina is clean. We do fuel maintenance for several marina storage tanks and always find water. Ask
to see the filter system your marina uses and when it was last changed.
W
hen
was
the
last
time
you
inspected
the
“O”
ring
gasket
on
your
deck
fuel
fill
cap?
Does
it
even
have
one?
Ever
clean
or
grease
it?
This
is
a
common
leak
point.
Decks
get
water
on
them
and
if
the
cap
leaks,
you
get
water
in
your
fuel.
Check
the
cap
and
clean
the
seal.
Replace
the
ring
if
it
is
worn
or
cracked
and
grease
it
with
a
good
fuel
and
waterproof,
synthetic
grease
like
SuperLube.
To
be
sure
it
closes
securely,
apply
a
thin
swipe
of
grease
or
black
paint
on
the
gasket
and
tighten
the
cap.
Remove
it
and
see
if
the
mating
surface
has
a
complete circle where the “O” ring makes contact, if not, get a new seal.
P
erhaps
the
most
common
leak
source
I
see
is
poorly
installed
fuel
vents.
All
vents
should
have
an
anti-siphon
loop
just
inside
where
the
vent
penetrates
the
hull.
This
is
a
loop
at
least
one
foot
above
the
vent
outlet
that
stops
spray,
rain,
or
sea
wash
from
entering
down
the
vent
hose
into
the
tank.
In
no
case
should
the
vent
hose
run
directly
down
to
the
tank.
Another
common
mistake
builders
make
is
installing
the
vents
upside
down.
Most
of
these
vents
have
small
side
holes
with
fine
screens
in
them.
These
holes
must
face
downward
and
slightly
aft
to
allow
water
to
drain
out.
You
may
think
because
your
boat
is
new
it
was
installed
correctly,
think
again.
We
see
poorly
installed
vents
on
the
finest
yachts
afloat!
Be
smart,
check
yours.
Water
in
the
fuel
is
not
as
common
as
asphaltenes,
but
it
can
shut
you
down
faster.
If
you
notice
any
water
in
your
fuel
filter
bowls, you can be sure there is more in your tank.