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 evapo-
rative canister. The canister temporarily holds the
vapors. The Powertrain Control Module (PCM) allows
intake manifold vacuum to draw vapors into the com-
bustion chambers during certain operating conditions.

All engines use a duty cycle purge system. The

PCM controls vapor flow by operating the duty cycle
EVAP purge solenoid (Refer to 25 - EMISSIONS
CONTROL/EVAPORATIVE

EMISSIONS/EVAP/

PURGE SOLENOID - OPERATION).

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

CCV SYSTEM

DESCRIPTION

The 8.3L V-10 engine is equipped with a Crankcase

Ventilation (CCV) system. The CCV system performs
the same function as a conventional PCV system, but

use a fixed orifice instead of vacuum controlled valve
(PCV valve).

OPERATION

It meters the amount of crankcase vapors drawn

out of the engine. The fixed orifice fitting is
mounted in each of the valve covers in the rear
of the engine (Fig. 1).

When the engine is operating, fresh air enters the

engine and mixes with crankcase vapors. Manifold
vacuum draws the vapor/air mixture through the
fixed orifice and into the intake manifold. The vapors
are then consumed during engine combustion.

Fig. 1 CC LOCATION

25 - 10

EVAPORATIVE EMISSIONS

DIAGNOSIS AND TESTING - CRANKCASE
VENTILATION SYSTEM

TESTING/CLEANING

The Crankcase Ventilation (CCV) system performs

the same function as a conventional PCV system, but
does not use a vacuum controlled valve. A vacuum
fitting containing a fixed orifice of a calibrated size is
used. It meters the amount of crankcase vapors
drawn out of the engine.

(1) Check each CCV system tube (line) for leaks,

cracks, kinks or bends. Replace as necessary

(2) Disconnect each CCV tube.
(3) Blow compressed air through each tube and

check for blockage or restrictions. If cleaning is nec-
essary, spray a soapy-type all-purpose cleaner into
each component and blow out. After restriction is
cleared, rinse out component with clear water. Blow
water from component and install to vehicle. To pre-
vent

damage

plastic

components,

never

spray carburetor-type cleaner into any of the
plastic tubes or the fixed orifice fitting. Never
attempt to clean the fixed orifice fitting with a
metal object as calibration could be affected. If
fixed fitting cannot be cleared, replace it.

EVAP/PURGE SOLENOID

OPERATION

The duty cycle EVAP purge solenoid regulates the

rate of vapor flow from the EVAP canister to the
throttle body. The Powertrain Control Module (PCM)
operates the solenoid.

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.

When purging the PCM energizes and de-energizes

the solenoid approximately 5 or 10 times per second,
depending upon operating conditions. The PCM var-
ies the vapor flow rate by changing solenoid pulse
width. Pulse width is the amount of time the solenoid
energizes.

CCV HOSE CONNECTION AT THROTTLE BODY

REAR CONNECTION FOR CCV

CCV HOSE

EVAPORATIVE EMISSIONS

25 - 11

CCV SYSTEM (Continued)

REMOVAL

The EVAP/Purge solenoid is located near the PCM

on the driver side of vehicle (Fig. 2).

(1) Disconnect the negative battery cable.
(2) Disconnect the electrical connector (Fig. 3).

(3) Remove the vacuum lines (Fig. 4).

(4) Pull solenoid up and off the mounting bracket

(Fig. 5).

Fig. 2 EVAP/PURGE SOLENOID LOCATION

Fig. 3 ELECTRICAL CONNECTOR

Fig. 4 VACUUM CONNECTION

Fig. 5 SOLENOID MOUNTING

1 - Mounting Bracket
2 - Rubber Grommet

25 - 12

EVAPORATIVE EMISSIONS

EVAP/PURGE SOLENOID (Continued)

INSTALLATION

(1) Make sure that you have the proper orientation

of the EVAP/Purge solenoid (Fig. 6).

(2) Install EVAP/Purge solenoid to the mounting

bracket (Fig. 5), make sure that the rubber grommet
in the solenoid fully when installed.

(3) Connect the vacuum lines.
(4) Connect the electrical connection
(5) Connect the negative battery cable.

FUEL FILLER CAP

DESCRIPTION

If the filler cap (Fig. 7) needs replacement, only

use a similar unit.

OPERATION

The fuel filler tube cap seals the fuel tank when

threaded onto the filler neck. For safety, the cap con-
tains pressure-vacuum relief valves. A malfunction in
the system or damage to the fuel lines could cause
excessive fuel tank pressure. The relief valves pre-
vent possible excessive pressure or vacuum build-up
in the fuel tank.

Removing the cap breaks the seal, relieving fuel

tank pressure.

LEAK DETECTION PUMP

REMOVAL

NOTE: The trunk panel (Fig. 8) will have to be cut to
remove the LDP pump.

(1) Disconnect the negative battery cable.
(2) Put access panel in place and scribe the outline

of the panel. Mark the hole for the rivet that hold the
panel in place.

Fig. 6 SOLENOID ORIENTATION

Fig. 7 Pressure Vacuum Filler Cap

1 - FUEL FILLER TUBE CAP
2 - GASKET

Fig. 8 TRUNK PANEL

EVAPORATIVE EMISSIONS

25 - 13

EVAP/PURGE SOLENOID (Continued)

Content .. 272 273 274 275 ..