Chrysler Pacifica. Manual — part 905
REMOVAL
(1) Disconnect the negative battery cable.
(2) Raise vehicle and support.
(3) Unlock and disconnect the electrical connector
(Fig. 6).
(4) Remove clamps and remove hoses.
(5) Press tab (Fig. 8) and release Natural Vacuum
Leak Detection pump (Fig. 7).
INSTALLATION
(1) Slide (Fig. 9) the Natural Vacuum Leak Detec-
tion pump (Fig. 10) onto the bracket and make sure
that the tab locks into the bracket.
Fig. 6 EVAP CANISTER AND NVLD
1 - Natural Vacuum Leak Detection Pump
2 - Pump Filter
3 - EVAP Canister
Fig. 7 UNLOCKING TAB FOR NVLD
Fig. 8 LOCKING TAB
Fig. 9 UNLOCKING TAB FOR NVLD
CS
EVAPORATIVE EMISSIONS
25 - 11
NATURAL VAC LEAK DETECTION ASSY (Continued)
(2) Install hoses and clamps.
(3) Connect the electrical connector (Fig. 11) and
lock.
(4) Lower vehicle.
(5) Connect the negative battery cable.
ORVR
OPERATION
The emission control principle used in the ORVR
system is that the fuel flowing into the filler tube
(appx. 1” I.D.) creates an aspiration effect which
draws air into the fill tube (Fig. 12). During refuel-
ing, the fuel tank is vented to the vapor canister to
capture escaping vapors. With air flowing into the
filler tube, there are no fuel vapors escaping to the
atmosphere. Once the refueling vapors are captured
by the canister, the vehicle’s computer controlled
purge system draws vapor out of the canister for the
engine to burn. The vapors flow is metered by the
purge solenoid so that there is no or minimal impact
on driveability or tailpipe emissions.
As fuel starts to flow through the fill tube, it opens
the normally closed check valve and enters the fuel
tank. Vapor or air is expelled from the tank through
the control valve to the vapor canister. Vapor is
absorbed in the canister until vapor flow in the lines
stops, either following shut-off or by having the fuel
level in the tank rise high enough to close the control
valve. The control valve (Refer to 14 - FUEL SYS-
TEM/FUEL DELIVERY/FUEL TANK - OPERATION)
contains a float that rises to seal the large diameter
vent path to the canister. At this point in the fueling
of the vehicle, the tank pressure increases, the check
valve closes (preventing tank fuel from spitting back
at the operator), and fuel then rises up the filler tube
to shut-off the dispensing nozzle.
If the engine is shut-off while the On-Board diag-
nostics test is running, low level tank pressure can
be trapped in the fuel tank and fuel can not be added
to the tank until the pressure is relieved. This is due
to the leak detection pump closing the vapor outlet
from the top of the tank and the one-way check valve
not allowing the tank to vent through the fill tube to
atmosphere. Therefore, when fuel is added, it will
back-up in the fill tube and shut off the dispensing
nozzle. The pressure can be eliminated in two ways:
1. Vehicle purge must be activated and for a long
enough period to eliminate the pressure. 2. Removing
the fuel cap and allowing enough time for the system
to vent thru the recirulation tube.
Fig. 10 LOCKING TAB
Fig. 11 NVLD/EVAP CANISTER ASSEMBLY
25 - 12
EVAPORATIVE EMISSIONS
CS
NATURAL VAC LEAK DETECTION ASSY (Continued)
Fig. 12 ORVR System Schematic
1 - FUEL TANK (PLASTIC)
11 - NATURAL VACUUM LEAD DETECTION (NVLD)
2 - FUEL FILLER TUBE
12 - LIQUID SEPARATOR (IF EQUIPPED)
3 - FUEL CAP (PRESSURE/RELIEF)
13 - ENGINE WIRING HARNESS TO NVLD
4 - FILL TUBE TO FUEL TANK CONNECTOR (ELASTOMERIC)
14 - VAPOR CANISTER
5 - TANK VENT/ROLLOVER VALVE(S)
15 - PURGE LINE
6 - VAPOR RECIRCULATION LINE
16 - PURGE DEVICE
7 - TANK VAPOR LINE
17 - WITHOUT NVLD
8 - VAPOR LINE TO CANISTER
18 - BREATHER ELEMENT
9 - CHECK VALVE (N/C)
19 - FLOW CONTROL ORIFICE
10 - CONTROL VALVE
20 - SERVICE PORT
21 - WITH NVLD
CS
EVAPORATIVE EMISSIONS
25 - 13
ORVR (Continued)
DIAGNOSIS AND TESTING - VEHICLE DOES
NOT FILL
CONDITION
POSSIBLE CAUSES
CORRECTION
Pre-Mature Nozzle Shut-Off
Defective fuel tank assembly
components.
Fill tube improperly installed
(sump)
Fill tube hose pinched.
Check valve stuck shut.
Control valve stuck shut.
Defective vapor/vent components.
Vent line from control valve to
canister pinched.
Vent line from canister to vent
filter pinched.
Canister vent valve failure
(requires double failure,
plugged to NVLD and
atmosphere).
Leak detection pump failed
closed.
Leak detection pump filter
plugged.
On-Board diagnostics evaporative
system leak test just conducted.
Canister vent valve vent
plugged to atmosphere.
Engine still running when
attempting to fill (System
designed not to fill).
Defective fill nozzle.
Try another nozzle.
Fuel Spits Out Of Filler
Tube.
During fill.
See Pre-Mature Shut-Off.
At conclusion of fill.
Defective fuel handling
component. (Check valve stuck
open).
Defective vapor/vent handling
component.
Defective fill nozzle.
25 - 14
EVAPORATIVE EMISSIONS
CS
ORVR (Continued)
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