Ford F150 Pickup. Manual — part 1349

8. Check Rear Aft-Axle Fuel Tank Solenoid Valve Operation

Reconnect rear aft-axle fuel tank solenoid valve harness connector C3126. Connect scan tool to DLC, if
not done previously. Turn ignition on. Using scan tool, enter OUTPUT TEST MODE. Press "Start"
button on scan tool to command all outputs on. Observe and record system pressure on fuel filler neck
venting kit gauge. Press "Stop" button on scan tool. If system pressure reading is zero psi (zero kPa) on
gauge when "Start" button is pressed, go to next step. If system pressure reading is more than zero psi
(zero kPa) on gauge when "Start" button is pressed, mark rear aft-axle fuel tank solenoid valve as
"Functions Normally" and go to step 11.

9. Check Rear Aft-Axle Fuel Tank Solenoid Valve Power Circuit For An Open

Turn ignition off. Disconnect rear aft-axle fuel tank solenoid valve harness connector C3126. Connect
DVOM between chassis ground and rear aft-axle fuel tank solenoid valve harness connector C3126
terminal No. 1 (Pink/Black wire). See Fig. 6. Turn ignition on. Using scan tool, enter OUTPUT TEST
MODE. Press "Start" button on scan tool to command all outputs on. Observe and record voltage reading
on DVOM. Press "Stop" button on scan tool. If voltage is more than 10 volts, go to next step. If voltage is
10 volts or less, repair open in Pink/Black wire. See ENGINE PERFORMANCE in appropriate SYSTEM
WIRING DIAGRAMS article in ELECTRICAL. Retest system for normal operation and go to step 11.

10. Check Rear Aft-Axle Fuel Tank Solenoid Valve Ground Circuit For An Open

Turn ignition off. Using DVOM, measure resistance between chassis ground and rear aft-axle fuel tank
solenoid valve harness connector C3126 terminal No. 2 (Black wire). See Fig. 6. If resistance is less than
5 ohms, mark rear aft-axle fuel tank solenoid valve as "Stuck Closed". A NEW solenoid valve will be
installed after diagnostics are completed. Go to step 11. If resistance is 5 ohms or more, repair open in
Black wire. See ENGINE PERFORMANCE in appropriate SYSTEM WIRING DIAGRAMS article in
ELECTRICAL. Retest system for normal operation and go to step 11.

11. Check Forward Aft-Axle Fuel Tank For An Open Solenoid Valve

Reconnect rear aft-axle fuel tank solenoid valve harness connector C3126. Close manual lock-down valve
jackscrew on rear aft-axle fuel tank. See Fig. 10. Tighten jackscrew to 62-79 INCH lbs. (7-9 N.m). Open
manual lock-down valve jackscrew on forward aft-axle fuel tank solenoid valve. Open manual bleed
valve on fuel filler neck venting kit for 60 seconds. Close manual bleed valve on fuel filler neck venting
kit. Observe system pressure on fuel filler neck venting kit gauge. If pressure on gauge is zero psi (zero
kPa), go to step 13. If pressure on gauge is more than zero psi (zero kPa), go to next step.

NOTE:

This procedure will supply power to fuel tank solenoid valve for
approximately 30-60 seconds. If time expires, cycle "Start/Stop" button on
scan tool to restore power.

NOTE:

This procedure will supply power to fuel tank solenoid valve for
approximately 30-60 seconds. If time expires, cycle "Start/Stop" button on
scan tool to restore power.

NOTE:

Ensure manual lock-down valve jackscrew on forward aft-axle fuel tank
solenoid valve is in open (full counterclockwise) position.

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE System & Component Testing - CNG

12. Check Forward Aft-Axle Fuel Tank Solenoid Valve Power Circuit For A Short To Voltage

Ensure ignition is off. Disconnect forward aft-axle fuel tank solenoid valve harness connector C3125.
Using DVOM, measure voltage between chassis ground and forward aft-axle fuel tank solenoid valve
harness connector C3125 terminal No. 1 (Pink/Black wire). Proceed as follows:

z

If voltage is 10 volts or more and vehicle is not equipped with an extended range fuel tank, repair
short to voltage in Pink/Black wire. See ENGINE PERFORMANCE in appropriate SYSTEM
WIRING DIAGRAMS article in ELECTRICAL. Replace solenoids marked "Stuck Open" or
"Stuck Closed" and retest system for normal operation.

z

If voltage is 10 volts or more and vehicle is equipped with an extended range fuel tank, repair short
to voltage in Pink/Black wire and go to step 16. See ENGINE PERFORMANCE in appropriate
SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

z

If voltage is less than 10 volts and vehicle is not equipped with an extended range fuel tank, replace
forward aft-axle fuel tank solenoid valve and all other solenoids marked "Stuck Open" or "Stuck
Closed". Retest system for normal operation.

z

If voltage is less than 10 volts and vehicle is equipped with an extended range fuel tank, mark
forward aft-axle fuel tank solenoid valve as "Stuck Open" and go to step 16.

13. Check Forward Aft-Axle Fuel Tank Solenoid Valve Operation

Ensure ignition is off. Reconnect forward aft-axle fuel tank solenoid valve harness connector C3125.
Connect scan tool to DLC, if not done previously. Turn ignition on. Using scan tool, enter OUTPUT
TEST MODE. Press "Start" button on scan tool to command all outputs on. Observe system pressure on
fuel filler neck venting kit gauge. Press "Stop" button on scan tool. If system pressure reading is zero psi
(zero kPa) on gauge when "Start" button is pressed, go to next step. If system pressure reading is more
then zero psi (zero kPa) on gauge when "Start" button is pressed, mark forward aft-axle fuel tank solenoid
valve as "Functions Normally". If vehicle is equipped with an extended range fuel tank, go to step 16. If
vehicle is not equipped with an extended range fuel tank, replace solenoids marked "Stuck Open" or
"Stuck Closed" and retest system for normal operation.

14. Check Forward Aft-Axle Fuel Tank Solenoid Valve Power Circuit For An Open

Turn ignition off. Disconnect forward aft-axle fuel tank solenoid valve harness connector C3125. Connect
DVOM between chassis ground and forward aft-axle fuel tank solenoid valve harness connector C3125
terminal No. 1 (Pink/Black wire). See Fig. 6. Turn ignition on. Using scan tool, enter OUTPUT TEST
MODE. Press "Start" button on scan tool to command all outputs on. Observe voltage reading on DVOM.
Press "Stop" button on scan tool. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or
less, repair open in Pink/Black wire. See ENGINE PERFORMANCE in appropriate SYSTEM WIRING
DIAGRAMS article in ELECTRICAL. If vehicle is equipped with an extended range fuel tank, go to step

NOTE:

This procedure will supply power to fuel tank solenoid valve for
approximately 30-60 seconds. If time expires, cycle "Start/Stop" button on
scan tool to restore power.

NOTE:

This procedure will supply power to fuel tank solenoid valve for
approximately 30-60 seconds. If time expires, cycle "Start/Stop" button on
scan tool to restore power.

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE System & Component Testing - CNG

16. If vehicle is not equipped with an extended range fuel tank, replace solenoids marked "Stuck Open"
or "Stuck Closed" and retest system for normal operation.

15. Check Forward Aft-Axle Fuel Tank Solenoid Valve Ground Circuit For An Open

Turn ignition off. Using DVOM, measure resistance between chassis ground and forward aft-axle fuel
tank solenoid valve harness connector C3125 terminal No. 2 (Black wire). Proceed as follows:

z

If resistance is 5 ohms or more and vehicle is not equipped with an extended range fuel tank, repair
open in Black wire and replace any solenoids marked "Stuck Open" or "Stuck Closed". See
ENGINE PERFORMANCE in appropriate SYSTEM WIRING DIAGRAMS article in
ELECTRICAL. Retest system for normal operation.

z

If resistance is 5 ohms or more and vehicle is equipped with an extended range fuel tank, repair
open in Black wire and go to next step. See ENGINE PERFORMANCE in appropriate SYSTEM
WIRING DIAGRAMS article in ELECTRICAL.

z

If resistance is less than 5 ohms and vehicle is not equipped with an extended range fuel tank,
replace rear aft-axle fuel tank solenoid valve and any other solenoid marked "Stuck Open" or
"Stuck Closed". Retest system for normal operation.

z

If resistance is less than 5 ohms and vehicle is equipped with an extended range fuel tank, mark
rear aft-axle fuel tank solenoid valve as "Stuck Closed" and go to next step.

16. Check Extended Range Fuel Tank For An Open Solenoid Valve

Ensure ignition is off. Reconnect forward aft-axle fuel tank solenoid valve harness connector C3125.
Close manual lock-down valve jackscrew on forward aft-axle fuel tank. See Fig. 10. Tighten jackscrew to
62-79 INCH lbs. (7-9 N.m). Open manual lock-down valve jackscrew on extended range fuel tank
solenoid valve. Open manual bleed valve on fuel filler neck venting kit for 60 seconds. Close manual
bleed valve on fuel filler neck venting kit. Observe system pressure on fuel filler neck venting kit gauge.
If pressure reading on gauge is zero psi (zero kPa), go to step 18. If pressure reading on gauge is more
than zero psi (zero kPa), go to next step.

17. Check Extended Range Fuel Tank Solenoid Valve Power Circuit For A Short To Voltage

Ensure ignition is off. Disconnect extended range fuel tank solenoid valve harness connector C3122.
Using DVOM, measure voltage between chassis ground and extended range fuel tank solenoid valve
harness connector C3122 terminal no. (Pink/Black wire). See Fig. 6. If voltage is 10 volts or more, repair
short to voltage in Pink/Black wire, replace any solenoids marked "Stuck Open" or "Stuck Closed". See
ENGINE PERFORMANCE in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
Retest system for normal operation. If voltage is 10 volts or less, replace extended range fuel tank
solenoid valve and any other solenoids marked "Stuck Open" or "Stuck Closed" and retest system for
normal operation.

NOTE:

Ensure manual lock-down valve jackscrew on extended range fuel tank
solenoid valve is in open (full counterclockwise) position.

NOTE:

This procedure will supply power to fuel tank solenoid valve for
approximately 30-60 seconds. If time expires, cycle "Start/Stop" button on

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE System & Component Testing - CNG

18. Check Extended Range Fuel Tank Solenoid Valve Operation

Ensure ignition is off. Reconnect extended range fuel tank solenoid valve harness connector C3122.
Connect scan tool to DLC, if not done previously. Turn ignition on. Using scan tool, enter OUTPUT
TEST MODE. Press "Start" button on scan tool to command all outputs on. Observe and record system
pressure on fuel filler neck venting kit gauge. Press "Stop" button on scan tool. If system pressure reading
is zero psi (zero kPa) on gauge when "Start" button is pressed, go to next step. If system pressure reading
is more than zero psi (zero kPa) on gauge when "Start" button is pressed, mark extended range fuel tank
solenoid valve as "Functions Normally" and replace all other solenoids marked "Stuck Open" or "Stuck
Closed". Retest system for normal operation.

19. Check Extended Range Fuel Tank Solenoid Valve Power Circuit For An Open

Turn ignition off. Disconnect extended range fuel tank solenoid valve harness connector C3122. Connect
DVOM between chassis ground and extended range fuel tank solenoid valve harness connector C3122
terminal No. 1 (Pink/Black wire). See Fig. 6. Turn ignition on. Using scan tool, enter OUTPUT TEST
MODE. Press "Start" button on scan tool to command all outputs on. Observe and record voltage reading
on DVOM. Press "Stop" button on scan tool. If voltage is more than 10 volts, go to next step. If voltage is
10 volts or less, repair open in Pink/Black wire and replace any solenoids marked "Stuck Open" or "Stuck
Closed". See ENGINE PERFORMANCE in appropriate SYSTEM WIRING DIAGRAMS article in
ELECTRICAL. Retest system for normal operation.

20. Check Extended Range Fuel Tank Solenoid Valve Ground Circuit For An Open

Turn ignition off. Using DVOM, measure resistance between chassis ground and extended range fuel tank
solenoid valve harness connector C3122 terminal No. 2 (Black wire). If resistance is less than 5 ohms,
replace extended range fuel tank solenoid valve and any other solenoids marked "Stuck Open" or "Stuck
Closed". Retest system for normal operation. If resistance is 5 ohms or more, repair open in Black wire
and replace any solenoids marked "Stuck Open" or "Stuck Closed". See ENGINE PERFORMANCE in
appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Retest system for normal
operation.

Testing (F150)

1. Check Rear In-Bed Fuel Tank Solenoid Valve For An Open

Turn ignition off. Connect grounding cable, venting hose assembly and fuel filler neck venting kit to vent
stack and fuel fill valve assembly. See Fig. 8 and Fig. 9 . Vent stack installation must be approved by
local authorities. For additional fuel tank venting information, see FUEL SYSTEM PRESSURE

scan tool to restore power.

NOTE:

This procedure will supply power to fuel tank solenoid valve for
approximately 30-60 seconds. If time expires, cycle "Start/Stop" button on
scan tool to restore power.

NOTE:

Battery must be fully charged to perform solenoid diagnostics. Ensure
manual lock-down valve jackscrew on rear in-bed fuel tank solenoid valve
is in open (full counterclockwise) position.

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE System & Component Testing - CNG