Repair concerns as necessary. If vehicle exhibits poor fuel economy, perform FUEL SYSTEM
PRESSURE RELEASE procedure under FUEL SYSTEM VENTING in appropriate REMOVAL &
INSTALLATION article. For a fuel smell symptom, go to step 16). For all other symptoms, go to next
step.
2) Check Fuel Tank Pressure
Turn ignition switch to OFF position. Install Filler Neck Venting Tool and Fuel Pressure Gauge from
Fuel Delivery System Special Tool Kit (134-00114) to vehicle fueling connector. Open by-pass valve,
located on fill valve. Refer to FUEL TANK VENTING procedure under COMPRESSED NATURAL
GAS FUEL SYSTEM PRESSURE RELEASE under FUEL SYSTEM VENTING in appropriate
REMOVAL & INSTALLATION article. Turn ignition switch to ON position. Record fuel tank pressure.
If fuel pressure reading is more than 500 psi (3448 kPa), turn ignition switch to OFF position. Close by-
pass valve. Remove fuel tank venting tool and go to step 7) (for no starts) or go to step 5). If fuel pressure
is 500 psi (3448 kPa) or less, turn ignition switch to OFF position. Check fuel level. Add fuel to tank if
necessary. If fuel level is okay, check for power at tank solenoid valve. Go to next step.
3) Check FSV PWR & GND Circuits To Fuel Tank Solenoid Shutoff Valve
Connect scan tool to Data Link Connector (DLC). Turn ignition switch to ON position. Using scan tool,
enter OUTPUT TEST MODE. Select ALL ON. Using a DVOM, measure voltage between FSV PWR
and GND circuits at fuel tank solenoid shutoff valve harness connector. See WIRING DIAGRAMS.
Fuel tank solenoid shutoff valve is located on fuel tank (one per tank). If voltage is 10.5 volts or less, go
to next step. If voltage is more than 10.5 volts, perform appropriate UNABLE TO VENT FUEL TANKS
OR FUEL LINES diagnostic procedures under FUEL SYSTEM (NATURAL GAS VEHICLES) in
appropriate SYSTEM & COMPONENT TESTING article to check for faulty fuel tank solenoid shutoff
valve. Replace as necessary.
4) Check For Open GND Circuit To Fuel Tank Solenoid Shutoff Valve
Using a DVOM, measure resistance between negative battery terminal and GND circuit at fuel tank
solenoid shutoff valve harness connector. If resistance is less than 5 ohms, repair open in FSV PWR
circuit to fuel tank solenoid shutoff valve. Verify symptom is no longer present. If resistance is 5 ohms or
more, repair open in GND circuit to fuel tank solenoid shutoff valve. Verify symptom is no longer
present.
5) Check Fuel Pressure
Use scan tool and access FRP PID from PID/DATA MONITOR & RECORD menu and monitor fuel
pressure. Turn ignition switch to ON position, with engine off. Record pressure reading. If the fuel
pressure reading is 80-120 psi (552-827 kPa), go to TEST DD, step 3). If the fuel pressure reading is not
80-120 psi (552-827 kPa), go to step 7).
NOTE:
When energized by scan tool, FSV PWR circuit to fuel tank solenoid
shutoff valve will remain ON for only 7 seconds.
WARNING:
Always refer to safety procedures to reduce possibility of injury. See
FUEL SYSTEM SAFETY PRECAUTIONS.
2003 Ford Pickup F150
2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline