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 instruction 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 instruction 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