Emissions Control: Overview Dodge Dart PF

Scheme 2

The evaporative emissions system is designed to control the release of fuel vapors into the atmosphere. The fuel tank check valve (4) and control valve (5) are used to reduce emissions due to the venting of vapor expansion within the fuel tank. When fuel evaporates from the fuel tank, vapors pass through a vent hose to the evaporative charcoal canister (3) where they are temporarily held. When the engine is running, the vapors are drawn into the intake manifold (8). In addition, fuel vapors produced during vehicle refueling are allowed to pass through the vent hose to the evaporative charcoal canister (3) for temporary storage (prior to being drawn into the intake manifold). The fuel tank check valve (4) and control valve (5) are non-serviceable components of the fuel tank assembly. The system is equipped with self-diagnosing capability using an Evaporative System Integrity Monitor (2). Refer to SWITCH, EVAPORATIVE EMISSIONS SYSTEM MONITOR, OPERATION .

The fuel tank pressure sensor (7) provides the PCM with information on vapor pressure inside the fuel tank. Excessive fuel tank pressure could cause fuel vapors to vent out the fuel filler cap or damage system components while insufficient fuel tank pressure (vacuum) caused by lack of fresh air entering the tank (1) to take the place of consumed fuel could lead to collapsed tank, lines or loss of fuel pressure.

The inlet check valve (6) prevents fuel from splashing back on the customer during vehicle refueling. This valve is also a non-serviceable component of the fuel tank assembly.

DESCRIPTION

The plastic fuel fill cap is a threaded/quarter turn onto the end of the fuel filler tube. Its purpose is to retain vapors and fuel in the fuel tank.

OPERATION

The loss of any fuel vapor out of fuel filler tube is prevented by the use of pressure-vacuum fuel fill cap. Relief valves inside the cap will release fuel tank pressure at predetermined pressures. Fuel tank vacuum will also be released at predetermined values. This cap must be replaced by a similar unit if replacement is necessary. This is in order for the system to remain effective.

A vacuum schematic for emission related items can be found on the vehicles VECI label. Refer to Vehicle Emission Control Information (VECI) Label for label location.

The ORVR (On-Board Refueling Vapor Recovery) system consists of a unique fuel tank, vapor control valve, one-way check valve and vapor canister.

The ORVR (On-Board Refueling Vapor Recovery) system is used to store and prevent the release into the atmosphere of the fuel tank vapors. This is done while the vehicle is being refueled.

Fuel flowing into the fuel filler tube (Approx. 1" I.D.) creates an aspiration effect drawing air into the fuel fill tube. During refueling, the fuel tank is vented to the EVAP 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 EVAP canister, the vehicle's computer controlled purge system draws vapor out of the canister for the engine to burn. The vapor 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 fuel 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 and on to the vapor canister. Vapor is absorbed in the EVAP canister until vapor flow in the lines stops. This stoppage occurs following fuel shut-off, or by having the fuel level in the tank rise high enough to close the control valve. This control valve contains a float that rises to seal the large diameter vent path to the EVAP canister. At this point in the refueling process, fuel tank pressure increases, the check valve closes (preventing liquid fuel from spiting back at the operator), and fuel then rises up the fuel filler tube to shut off the dispensing nozzle.

Scheme 3

The fuel tank pressure sensor provides the PCM with information on vapor pressure inside the fuel tank. The sensor is a diaphragm-type pressure sensor and varies its voltage output depending on fuel tank pressure. When the fuel tank isolation valve is activated (closed), preventing fuel vapors from leaving the tank, the PCM will monitor the fuel tank pressure sensor to prevent pressure from increasing or decreasing to an unsafe level.

Excessive fuel tank pressure could cause fuel vapors to vent out the fuel filler cap or damage system components while insufficient fuel tank pressure (vacuum) caused by lack of air entering the tank to take the place of consumed fuel could lead to collapsed tank, lines or loss of fuel pressure.

Scheme 4

Scheme 5

Scheme 6

1. Disconnect and isolate the negative battery cable.
2. Remove the fuel filler cap to relieve tank pressure.
3. Partially raise the vehicle.
4. Remove the right rear wheel splash shield. Refer to «SHIELD, SPLASH, REAR WHEELHOUSE, REMOVAL»(ref-646233-S11862273022014072800000) .
5. Disconnect the fuel tank pressure sensor electrical connector (1).
6. Carefully raise the retaining tab (2), rotate and remove the fuel tank pressure sensor (1) from the fuel tank vent tube.
7. The fuel tank pressure sensor seal (1) can be reused if not damaged.

Scheme 7

1. The fuel tank pressure sensor seal (1) can be reused if not damaged.
2. Install the fuel tank pressure sensor (1) into the fuel tank vent tube and rotate into position.
3. Connect the fuel tank pressure sensor electrical connector (1).
4. Install the right rear wheel splash shield. Refer to «SHIELD, SPLASH, REAR WHEELHOUSE, INSTALLATION»(ref-646233-S21019795112014072800000) .
5. Lower the vehicle.
6. Install the fuel filler cap.
7. Connect the negative battery cable and tighten nut to 5 N.m (45 in. lbs.).

Scheme 8

Scheme 9

1. Disconnect and isolate the negative battery cable.
2. Remove the belly pan (1). Refer to «BELLY PAN, REMOVAL»(ref-646214-S24731623582014072800000) .
3. Disconnect the lower purge control valve (3) wire harness connector (1).
4. Disconnect the vacuum hose from the lower purge control valve (3).
5. Remove bolt (2) and the lower purge control valve (3).

Scheme 10

Scheme 11

1. Disconnect and isolate the negative battery cable.
2. Remove the air cleaner body (1). Refer to «BODY, AIR CLEANER, REMOVAL»(ref-646215-S35238296702014072800000) .
3. Disconnect the purge control valve (1) wire harness connector (3).
4. Disconnect the vapor line (2) from the purge control valve (1). Refer to «FITTING, QUICK CONNECT, STANDARD PROCEDURE»(ref-646230-S25407444222014072800000) .
5. Disconnect the vacuum hose (5) from purge control valve (1).
6. Remove the purge control valve (1) from the intake manifold support bracket (4).

Scheme 12

Scheme 13

Scheme 14

Scheme 15

1. Disconnect the negative battery cable.
2. Loosen the air resonator clamp (2).
3. Disconnect the air temperature sensor electrical connector.
4. Remove the engine cover.
5. Remove the quick connect fuel tank hose (4) from evaporator purge valve. NOTE: The foam isolator is molded into the intake manifold. Removing the foam isolator may require the engine to be rotated towards the front of the engine compartment.
6. Using care, roll the foam isolator (2) away from the purge valve.
7. Disconnect electrical connector (1) from evaporator purge valve (2).
8. Remove purge hose (3) from purge valve (2).
9. Remove the evaporator purge valve from the bracket (4).