Chrysler 300M, Dodge Interpid. Manual — part 406

sion of fuel tank vapors into the atmosphere. When
fuel evaporates in the fuel tank, the vapors pass
through vent hoses or tubes to an activated carbon
filled evaporative canister. The canister temporarily
holds the vapors. The Powertrain Control Module
(PCM) allows intake manifold vacuum to draw
vapors into the combustion chambers during certain
operating conditions (Fig. 1).

All engines use a proportional purge solenoid sys-

tem. The PCM controls vapor flow by operating the
purge solenoid. Refer to Proportional Purge Solenoid
in this section.

NOTE: The evaporative system uses specially man-
ufactured hoses. If they need replacement, only use
fuel resistant hose. Also the hoses must be able to
pass an Ozone compliance test.

NOTE: For more information on Onboard Refueling
Vapor Recovery (ORVR), refer to the Fuel Delivery
section.

EVAPORATIVE EMISSIONS

25 - 11

EVAP/PURGE SOLENOID

DESCRIPTION

All vehicles use a proportional purge solenoid. The

solenoid regulates the rate of vapor flow from the
EVAP canister to the throttle body. The PCM oper-
ates the solenoid.

OPERATION

During the cold start warm-up period and the hot

start time delay, the PCM does not energize the sole-
noid. When de-energized, no vapors are purged.

The proportional purge solenoid operates at a fre-

quency of 200 hz and is controlled by an engine con-
troller circuit that senses the current being applied
to the proportional purge solenoid (Fig. 2) and then

adjusts that current to achieve the desired purge
flow. The proportional purge solenoid controls the
purge rate of fuel vapors from the vapor canister and
fuel tank to the engine intake manifold.

REMOVAL

The solenoid attaches to a bracket near the air

cleaner. The solenoid will not operate unless it is
installed correctly.

(1) Disconnect electrical connector from solenoid.
(2) Disconnect vacuum tubes from solenoid.
(3) Remove solenoid from bracket.

INSTALLATION

The solenoid attaches to a bracket near the air

cleaner. The solenoid will not operate unless it is
installed correctly.

Fig. 1 ORVR System Schematic

1 - FUEL TANK (PLASTIC)
2 - FUEL FILLER TUBE
3 - FUEL CAP (PRESSURE/RELIEF)
4 - FILL TUBE TO FUEL TANK CONNECTOR (ELASTOMERIC)
5 - TANK VENT/ROLLOVER VALVE(S)
6 - VAPOR RECIRCULATION LINE
7 - TANK VAPOR LINE
8 - VAPOR LINE TO CANISTER
9 - CHECK VALVE (N/C)
10 - CONTROL VALVE
11 - NATURAL VACUUM LEAD DETECTION (NVLD)

12 - LIQUID SEPARATOR (IF EQUIPPED)
13 - ENGINE WIRING HARNESS TO NVLD
14 - VAPOR CANISTER
15 - PURGE LINE
16 - PURGE DEVICE
17 - WITHOUT NVLD
18 - BREATHER ELEMENT
19 - FLOW CONTROL ORIFICE
20 - SERVICE PORT
21 - WITH NVLD

25 - 12

EVAPORATIVE EMISSIONS

EVAPORATIVE EMISSIONS (Continued)

The top of the solenoid has TOP printed on it. The

solenoid will not operate unless it is installed cor-
rectly.

(1) Install solenoid on bracket.
(2) Connect vacuum tube to solenoid.
(3) Connect electrical connector to solenoid.

FUEL FILLER CAP

DESCRIPTION

The plastic fuel fill cap is threaded/quarter turn

onto the end of the fuel filler tube. It’s purpose is to
retain vapors and fuel in the fuel tank.

OPERATION

The fuel filler cap incorporates a two-way relief

valve that is closed to atmosphere during normal
operating conditions. The relief valve is calibrated to
open when a pressure of 17 kPa (2.5 psi) or vacuum
of 2 kPa (0.6 in. Hg) occurs in the fuel tank. When
the pressure or vacuum is relieved, the valve returns
to the normally closed position.

CAUTION: Remove the fuel filler cap to release fuel
tank pressure before disconnecting any fuel system
component.

NATURAL VAC LEAK
DETECTION ASSY

DESCRIPTION

The natural Vacuum Leak detection (NVLD) sys-

tem is mounted on top of the EVAP canister (Fig. 3)
that is mounted on the fuel tank.

REMOVAL

(1) Disconnect the negative battery cable.
(2) Remove fuel tank, refer to the Fuel Delivery

section for Fuel Tank Removal.

(3) Disconnect the electrical connector from the

NVLD assembly.

(4) Disconnect the hoses from the NVLD assembly

(Fig. 5).

(5) Lift tab on NVLD assembly (Fig. 4) and twist

the assembly counterclockwise and pull up to remove
from EVAP canister (Fig. 5).

(6) Remove O-ring from EVAP canister (Fig. 6).

Fig. 2 UPSTREAM HEATED OXYGEN SENSOR 1/1

1 - PROPORTIONAL PURGE SOLENOID
2 - O2 SENSOR

Fig. 3 NVLD ASSEMBLY

EVAPORATIVE EMISSIONS

25 - 13

EVAP/PURGE SOLENOID (Continued)

INSTALLATION

(1) Install O-ring to EVAP canister (Fig. 6).
(2) Install NVLD assembly (Fig. 4) and twist the

assembly clockwise to lock assembly in the EVAP
canister (Fig. 5).

(3) Connect the hoses to the NVLD assembly.
(4) Connect the electrical connector to the NVLD

assembly.

(5) Install fuel tank, refer to the Fuel Delivery sec-

tion for Fuel Tank Installation.

(6) Connect the negative battery cable.

ORVR

DESCRIPTION

Onboard Refueling Vapor Recovery (ORVR) System

Schematic and components (Fig. 7).

OPERATION

The emission control principle used in the ORVR

system is that the fuel flowing into the filler tube
(approx. 1” I.D.) creates an aspiration effect which
draws air into the fill tube. During refueling, the fuel
tank is vented to the vapor canister to capture escap-
ing 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 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 pres-
sure increase, the check valve closes (preventing tank
fuel from spiting back at the operator), and fuel then
rises up the filler tube to shut-off the dispensing noz-
zle.

Fig. 4 LOCKING TAB

Fig. 5 ASSEMBLY REMOVED

Fig. 6 O-RING

25 - 14

EVAPORATIVE EMISSIONS

NATURAL VAC LEAK DETECTION ASSY (Continued)

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Chrysler 300M, Dodge Interpid. Manual — part 406

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