2003 FORD MUSTANG fuel pressure

z
is located in the right front inner fender well.
The fuel vapor control valve tube assembly:
zconsists of the fuel vapor control valve, fuel vapor vent valve and an in- line fuel tank pressure
sensor.
z prevents suspended liquid fuel from being drawn into the evaporative emission canister along
with the fuel vapors.
z returns the liquid to the fuel tank.
z includes a fresh air transfer tube routing fresh air between the canister vent solenoid hose and
the fuel tank filler pipe assembly.
z requires two grommets to seal the fuel vapor control valve and fuel vapor vent valve to the fuel
tank.
The evaporative emission (EVAP) system monitor:
zis a self- test strategy within the PCM, which tests the integrity of the EVAP system.
z monitors the EVAP system for leaks.
z monitors electronic EVAP components for irrationally high or low voltages.
z monitors for correct EVAP system operation.
z utilizes intake manifold vacuum to test the EVAP system and involves several stages.
The evaporative emission (EVAP) test port:
zis used to connect the Evaporative Emission System Leak Tester to the EVAP system.
z is located on the EVAP canister purge outlet tube near the EVAP canister purge valve. Klj . 3 ba
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DIAGNOSIS AND TESTING
Evaporative Emissions
Evaporative Emission System
SECTION 303-
13: Evaporative Emissions 2003 Mustang Workshop Manual Special Tool(s)
Evaporative Emission System
Leak Tester
310-
F007 (134- 00056) or
equivalent Worldwide Diagnostic System
(WDS)
418-
F224,
New Generation STAR (NGS)
Tester
418- F052, or equivalent scan
tool Item Part Number Description
1 9030 Fuel filler cap
2 9B593 Fuel vapor vent valve
3 9C052 Fuel tank pressure sensor
4 9C915 Evaporative emission canister purge valve
5 9F945 Canister vent solenoid
6 9D653 Evaporative emission canister
7 9002 Fuel tank
8 9B190 Fuel vapor control valve
9 9189 Fuel filler pipe check valve Klj . 1 ba
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Principles of Operation
Evaporative Emission (EVAP) Canister Purge Valve
The EVAP canister purge valve is controlled by the powertrain control module (PCM). The EVAP
canister purge valve controls the flow of fuel vapors from the EVAP canister to the engine intake
manifold during various engine operating modes. The EVAP canister purge valve is normally closed.
Evaporative Emission (EVAP) Canister
Fuel vapors from the fuel tank are stored in the EVAP canister. When the engine is running, the vapors
are purged from the EVAP canister for combustion.
Canister Vent Solenoid
During the Evaporative Emission (EVAP) System Test Monitor, Evaporative Emissions Repair
Verification Drive Cycle, and the Evaporative Emission System Leak Test, the canister vent solenoid is
closed to allow a vacuum to be drawn on the fuel tank at a specific level. The canister vent solenoid is
normally open.
Fuel Tank Pressure (FTP) Sensor
The fuel tank pressure sensor is used to measure the fuel tank pressure during the Evaporative
Emissions Monitor Test. The fuel tank pressure sensor is mounted in the fuel vapor control valve tube
as it crosses over the fuel tank.
Fuel Vapor Control Valve
The fuel vapor control valve is normally between the EVAP canister and the fuel vapor vent valve. Its
function is to prevent the flow of liquid fuel into the EVAP canister or up to the canister purge valve
during refueling, and to prevent the collection of liquid fuel in the fuel vapor hoses by overfilling the fuel
tank.
Fuel Vapor Vent Valve (FVV) Assembly
The fuel vapor vent valve (FVV) assembly is mounted on the top of the fuel tank. It is used to control
the flow of fuel vapors entering the EVAP system. The head portion of the assembly prevents the fuel
tank from overfilling during refueling. The assembly also has a spring float, which prevents liquid fuel
from entering the vapor delivery system under severe handling or vehicle rollover conditions. In the
upright position, the open bottom of the float will lift and shut off the orifice. Under severe handling
conditions, the spring will push the float closed when angles allow liquid fuel to reach the orifice. In a
rollover condition, the weight of the open bottom float and spring pressure will close the orifice.
Fuel Filler Pipe Check Valve
The fuel filler pipe check valve is an intricate part of the fuel filler pipe. It is intended to prevent liquid
fuel from re-entering the fuel filler pipe from the fuel tank on refueling or roll over conditions.
Fuel Filler Cap
The fuel filler cap is used to prevent fuel spill and to close the EVAP system to the atmosphere.
Evaporative Emission System Monitor
When a fault occurs, the EVAP system monitor is reset to NO and a diagnostic trouble code (DTC) is
set in the PCM memory. After the DTC is repaired, the vehicle drive cycle must be completed to reset
the monitor in preparation for inspection and maintenance testing. EVAP Emission System Leak Test Klj . 2 ba
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To start the testing, conditions of stable purging and vehicle speed must be satisfied. During the first
stage, the canister vent solenoid is closed, while the EVAP canister purge valve remains open,
applying and building vacuum in the system as indicated by the FTP sensor. This phase checks for
major leaks in the EVAP system.
In the second stage, the EVAP canister purge valve closes and the system looks for minimal decay
rate in the EVAP vacuum, indicating the absence of any small EVAP system leaks.
The last stage is entered only if stage two of the leak test has failed and checks whether the failed test
was due to excess vapor generation. It monitors fuel vapor generation rate. Initially, the canister vent
solenoid is opened to equalize EVAP system pressure to atmosphere. Then the canister vent solenoid
is closed, allowing pressure to build if vapor generation is present in sufficient quantity. If the rate of
generation is found to be too high, the EVAP running loss system leak test is aborted. If not, then a
small leak is diagnosed.
On-
Board Refueling Vapor Recovery (ORVR) Evaporative Emission (EVAP) System
The basic elements forming the ORVR system are as follows:
zThe fuel filler pipe forms a seal to prevent vapors from escaping the fuel tank while liquid is
entering the fuel tank. Liquid in the one inch diameter tube blocks vapors from rushing back up
the fuel filler pipe.
z A fuel vapor control valve controls the flow of vapors out of the fuel tank. The valve closes when
the liquid level reaches a height associated with fuel tank usable capacity. The valve
accomplishes the following:
„limits the total amount of fuel that can be dispensed into the fuel tank
„ prevents liquid gasoline from exiting the fuel tank when submerged (as well as when
tipped well beyond a horizontal plane as part of the vehicle rollover protection in road
accidents)
„ minimizes vapor flow resistance during anticipated refueling conditions
z Fuel vapor tubing connects the fuel vapor control valve to the EVAP canister. This routes the
fuel tank vapors, displaced by the incoming liquid, to the EVAP canister.
z A check valve in the fuel filling system prevents liquid from rushing back up the fuel filler pipe
during the liquid flow variations associated with the filler nozzle shut- off.
Between refueling events, the EVAP canister is purged with fresh air so that it may be used again to
store vapors accumulated during engine soaks or subsequent refueling events. The vapors drawn off
of the carbon in the EVAP canister are consumed by the engine.
Inspection and Verification 1. Verify the customer concern is with the evaporative emission (EVAP) system.
2. Visually inspect for the following obvious signs of mechanical damage.
Visual Inspection Chart Mechanical
z
Fuel filler cap
z EVAP test port
z EVAP canister or canister vent solenoid Klj . 3 ba
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manifold.
z Complete the evaporative emission
system leak test. Refer to Evaporative Emission System Leak Test in this
section.
z Does the system pass the leak test? No
GO to
A4 .
A3 VISUALLY INSPECT THE FUEL
FILLER CAP z
Visually inspect the fuel filler cap for
damage.
z Is the fuel filler cap damaged? Yes
INSTALL a new fuel filler cap. GO to
A4 .
No
GO to A4 .
A4 CHECK FOR SMALL LEAKS AT THE
FUEL FILLER CAP AND EVAP TEST PORT z
Connect the Evaporative Emission
System Leak Tester to the fuel filler
pipe.
z Key in ON position.
z Close the canister vent solenoid. Refer
to Canister Vent Solenoid Closing Procedure in this section.
z Pressurize the EVAP system to 3.48
kPa (14 inches H
2 O).
z Using the ultrasonic leak detector,
check the fuel filler cap and EVAP test
port for leaks.
z Is a leak detected? Yes
REPAIR or INSTALL new components as
necessary. GO to
A5 .
No
INSTALL the fuel filler cap. CARRY OUT the
evaporative emission system leak test. REFER
to Evaporative Emission System Leak Test in
this section. If the system passes the leak test,
CARRY OUT the evaporative emissions repair
verification drive cycle. REFER to Evaporative Emission Repair Verification Drive Cycle in this
section. A5 CHECK FOR CONCERN OTHER THAN
THE FUEL FILLER CAP z
Refer to previous test results.
z Did the system pass the evaporative
emission system leak test carried
out in pinpoint test Step A2? Yes
CARRY OUT the evaporative emission system
leak test. REFER to
Evaporative Emission System Leak Test in this section. If the system
passes the leak test, CARRY OUT the
evaporative emission repair verification drive
cycle. REFER to Evaporative Emission Repair Verification Drive Cycle in this section.
No
INSTALL the fuel filler cap. GO to A6 .
A6 CHECK FOR SMALL LEAK WITH
TESTER SET AT FILL POSITION z
Connect the Evaporative Emission
System Leak Tester to the EVAP test
port.
z Key in ON position.
z Close the canister vent solenoid. Refer
to Canister Vent Solenoid Closing Procedure in this section.
z Turn the selector on the Evaporative
Emission System Leak Tester to the
FILL position.
z Pressurize the EVAP system to 3.48
kPa (14 inches H
2 O).
z Does the pressure on the EVAP
system hold between 3.43 kPa and
3.53 kPa (13.80 inches and 14.20 Yes
GO to
A7 .
No
DISCONTINUE pressurizing the system. GO to
A8 . Klj . 6 ba
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PINPOINT TEST B: DTC P0455 MAJOR LEAK OR NO FLOW
DETECTED OR DTC P1443 VERY SMALL OR NO PURGE FLOW
DETECTED IN SYSTEM Procedure in this section.
z Pressurize the EVAP system to 3.48
kPa (14 inches H
2 O).
z Using the ultrasonic leak detector,
check the fuel vapor control valve tube
to the fuel tank for leaks. Check the
fuel tank pressure sensor, fuel vapor
control valve tube and the fuel filler
pipe. Check fuel tank to EVAP canister
-canister vent solenoid.
z Is a leak detected? A10 CHECK EVAP SYSTEM AT FUEL
FILLER PIPE z
Reconnect the EVAP canister purge
outlet tube to the fuel vapor tee.
z Complete the evaporative emission
system leak test. Refer to Evaporative Emission System Leak Test in this
section.
z Does the EVAP system pass the
leak test? Yes
RESTORE the system to normal operation.
CARRY OUT the evaporative emission system
leak test. REFER to
Evaporative Emission System Leak Test in this section. If the system
passes the leak test, CARRY OUT the
evaporative emissions repair verification drive
cycle. REFER to Evaporative Emission Repair Verification Drive Cycle in this section.
No
GO to A6 .
Test Step Result / Action to Take
NOTE:
Condition DTC P0455 set: – 1.74 kPa (-7.0 inches H
2 O) over 30 seconds. NOTE:
Condition DTC P1443 set: – 1.74 kPa (-7.0 inches H
2 O) over 30 seconds with more than
0.02 lb/min vapor flow. B1 CHECK FOR DIAGNOSTIC
TROUBLE CODE P0455 OR
P1443 z
Use the recorded results
from the PCM DTCs.
z Is DTC P0455 present? Yes
GO to
B2 .
No
GO to B3 .
B2 VISUALLY CHECK FOR
GROSS EVAP SYSTEM LEAKS z
Check for the presence of a
fuel filler cap. Do not tighten
or check for correct
installation at this time.
z Check the input port
vacuum and EVAP return
tube are connected to the
EVAP canister purge valve.
z Check that the canister vent
solenoid is correctly
attached to the EVAP Yes
REPAIR or INSTALL new EVAP components as necessary.
GO to
B3 .
No
GO to B3 . Klj . 8 ba
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canister.
z Check for disconnected or
cracked fuel vapor hoses or
tubes between the intake
manifold and following
components:
„EVAP canister purge
valve
„ EVAP canister
„ fuel vapor vent valve
assembly
„ fuel vapor control
valve tube assembly
z Check for damaged fuel
tank or fuel filler pipe.
z Is a concern with a hose,
tube, connection or valve
visually evident? B3 CHECK FOR EVAP SYSTEM
LEAKS z
Disconnect the EVAP return
tube from the intake
manifold and plug the EVAP
return tube.
z Connect the Evaporative
Emissions System Leak
Tester to the EVAP test
port.
z Carry out the evaporative
emissions system leak test.
Refer to Evaporative Emission System Leak Test
in this section.
z Does the system pressure
stay above 1.99 kPa (8
inches H
2 O)? Yes
GO to
B4 .
No
VERIFY that the fuel filler cap is installed correctly. REPAIR
or INSTALL new components as necessary. CARRY OUT
the evaporative emission system leak test. REFER to
Evaporative Emission System Leak Test in this section. If
the system passes the leak test, CARRY OUT the
evaporative emission repair verification drive cycle. REFER
to Evaporative Emission Repair Verification Drive Cycle in
this section. B4 CHECK FOR BLOCKAGE
BETWEEN THE EVAP
CANISTER PURGE VALVE AND
FUEL VAPOR TEE z
Key in ON position.
z Close the canister vent
solenoid. Refer to Canister Vent Solenoid Closing
Procedure in this section.
z Pressurize the EVAP
system to 3.48 kPa (14
inches H
2 O).
z Open the canister vent
solenoid. Refer to Canister Vent Solenoid Closing
Procedure in this section.
z Does the pressure drop
immediately? Yes
GO to
B5 .
No
INSTALL a new vapor line between the EVAP canister
purge valve and the fuel vapor tee. CARRY OUT the
evaporative emission system leak test. REFER to
Evaporative Emission System Leak Test in this section. If
the system passes the leak test, CARRY OUT the
evaporative emission repair verification drive cycle. REFER
to Evaporative Emission Repair Verification Drive Cycle in
this section. B5 CHECK FOR BLOCKAGE
BETWEEN FUEL FILLER PIPE
AND THE FUEL VAPOR TEE z
Connect the Evaporative
Emissions System Leak Yes
GO to
B6 . Klj . 9 ba
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PINPOINT TEST C: DTC P1450 EXCESSIVE VACUUM DETECTED IN
THE FUEL TANK Tester to the fuel filler pipe.
z Pressurize the EVAP
system to 6.47 to 6.97 kPa
(26 to 28 inches H
2 O).
z Does the pressure drop
immediately? No
INSTALL new fuel tank vapor line(s). REPEAT pinpoint test
Step B5 to verify the repair. CARRY OUT the evaporative
emission system leak test. REFER to
Evaporative Emission System Leak Test in this section. If the system passes the
leak test, CARRY OUT the evaporative emission repair
verification drive cycle. REFER to Evaporative Emission Repair Verification Drive Cycle in this section.
B6 CHECK FOR FAILED EVAP
CANISTER PURGE VALVE OR
FUEL TANK PRESSURE
SENSOR z
Use the recorded results
from the PCM DTCs.
z Are DTC codes P0455 and
P1443 present? Yes
INSTALL a new EVAP canister purge valve. REFER to
Evaporative Emission Canister Purge Valve
in this section.
CARRY OUT the evaporative emission system leak test.
REFER to Evaporative Emission System Leak Test in this
section. If no leak is detected, CARRY OUT the evaporative
emissions repair verification drive cycle. REFER to
Evaporative Emission Repair Verification Drive Cycle in this
section.
No
INSTALL a new fuel tank pressure sensor. REFER to Fuel Tank Pressure Sensor in this section. CARRY OUT the
evaporative emission system leak test. REFER to
Evaporative Emission System Leak Test in this section. If
the system passes the leak test, CARRY out the
evaporative emission repair verification drive cycle. REFER
to Evaporative Emission Repair Verification Drive Cycle in
this section. Test Step Result / Action to Take
NOTE:
Condition P1450 DTC set: more than - 1.79 kPa (-7.2 inches H
2 O) over 30 seconds. C1 CHECK FOR VISUAL CAUSES OF EXCESSIVE
FUEL TANK VACUUM z
Check for kinks or bends in the fuel vapor hoses
and tubes.
z Visually check the EVAP canister inlet port,
canister vent solenoid filter or outlet hose for
contamination or foreign material.
z Check the canister vent solenoid for blockage or
contamination.
z Is a concern with a hose, tube, connection or
component visually evident? Yes
REMOVE any contamination or foreign
material around fuel vapor hoses and
tubes. REPAIR the hoses, tubes or
components as necessary. After all
visual concerns are repaired, GO to
C2
.
No
GO to C2 .
C2 CHECK FOR BLOCKAGE BETWEEN EVAP
TEST PORT AND CANISTER VENT SOLENOID z
Disconnect and plug the EVAP return tube at the
intake manifold.
z Connect the Evaporative Emissions System Leak
Tester to the EVAP test port. Yes
GO to
C3 .
No Klj . 10 ba
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