Evaporative Emission Control System Inspection - Datsun 620 Series 1977 Service Manual

J
1 Fuel tank
2 Fuel f1l1er cap with
vacuum
relief valve
3
Liquid
vapor separator
4
Vapor
vent line
5 Vacuum
signalUne
As
the throttle valve opens and
vehicle
speed
increases
vacuum
pres
sure
in
the vacuum signal line forces
rHL
JL
I
EC785
INSPECTION
FUEL
TANK
VAPOR
LIQUID
SEPARATOR
AND
VAPOR
VENT LINE
I Check all
hoses and fuel tank
mler
cap
2 Disconnect the
vapor
vent
line
connecting carbon canister
to
vapor
liquid
separator
3 Connect
a
3 way connector
a
Emission
Control System
Close
at idling
Open
at rest
i
J
17
f
Fuel
vapor
6 Canister purge line
7 Throttlevalv
8
Engine
9 Carbon canister
10 Activated carbon
11 Screen
12 Filter
13
Purge
control valve
14
Spring
15
Diaphragm
16 Fixed orifice
i
j
EC784
Fig
EC 77
Evaporative
emu ion control
sy tem
Fuel
vapor
flow
when
engine
i6 at
red
or
idling
the purge control valve
to
open
and
admits
an
orifice
to
intake manifold
and fuel
vapor is
then drawn
into
the
I
J
o I
Fuel
vapor
Fresh air
intake
manifold
through
the canister
purge line See
Figure EC 7B
Fig EC 78 Evaporative emiuion control system
Fuel vapor flow when engine i running
manometer
and
a
cock
or an equiva
lent
3 way
charge cock to the end of
the
vent
line
4
Supply
fresh
air into
the vapor
vent
line
through
the cock little by
little until
pressure
becomes 368
mrnH20
14
5 inH20
5 Shut the cock
completely
and
leave it unattended
6 After 2 5
minutes
measure
the
height of the liquid
in
the
manometer
7
Variation of height should
remain
EC 31
with 25 mmH20 0 98 inH20
8 When filler cap does not
close
completely the height
should drop
to
zero
in
a
short
time
9 I f
the height does
not drop to
zero
in
a
short time
when filler cap is
removed it is the
cause
of
a
stuffy
hose
Note
In
case
the vent
line
is stuffy
the
breathing in
fuel tank
is
not
thoroughly
made thus
causing
in