EMISSION
AND
EVAPORATIVE LOSS CONTROL SYSTEMS
Function
Checks
Warm
the engine
to
normal runnmg temperature. Ensure that
the Idle speed returns
to
normal
Blip the throttle and observe
the
valve.
which
should open and close as the engine speed
changes.
If the valve is
nOI
operatmg. remove the
E.G.
A.
valve and
check the valve operation
usmg a vacuum test gauge.
Fit
a
new
EG R valve if
It
1$
found
to
be defective.
Crankcase
Breathing
To ensure that piston
'blow
by' gases do not escape from the
crankcase to the atmosphere, a depression
1$ maintained
In
the crankcase under all operatmg conditions.
This
IS
achIeved
by connecting the crankcase breathing
hOUSing
10
a
POIi'll
between the air meter flap and the throttle plate
ie.
a
constant depression region,
On
Rover
3500
and
TRS
models air
is
drawn into the right
hand
rock.er
cover
via
an air filter and restnctor and drawn off
from the engine on the left hand
rock.er
cover. A flame trap
is
fitted
In
the
draw
off housing.
Evaporative
Loss
Control
System
The function
of
this control system
IS
to
prevent fuel
hydrocarbon vapours from entenng the atmosphere. This
IS
achllwed by providing
no
external fuel
tank.
breathing system
and
as
an alternative venting the tank through
two
adsorption
canisters located
In
the engine compartment.
To
prevent the canisters flooding due to thermal expanSion of
any fuel
in
the tank. the tank filler neck
IS
entered well
down
Into the tank, and a pipe let into the tank at
maximum
fuel
level vents into the filler neck
to
allow
for fuel expansion. A
liqUid vapour separator
IS
Incorporated into the fuel tank vent
Pipe to reduce the quantity of vapour passed to the canisters.
Any fuel vapour
IS
purged from the canisters once the engine
IS
running by means of a connection to a constant depreSSion
region between the air meter flaps and the throttle butterfly.
WARNING:
The
use
of
compressed
air
to
clean
an
adsorption
canister
or
clear
a
blockage
in
the
evaporative
system
is
very
dangerous.
An
explosive
gas
present
in
a
partly
saturated
canister
may
be
ignited
by
the
heat
generated
when
compressed
air
passes
through
the
canister.
21
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