Ford F150 Pickup. Instruction - part 1150

15. Fuel Tank Straps: Examine the fuel tank straps for correct positioning of the rubber isolators. Replace the 

rubber isolators as necessary.  

16. Inspection Record: Record the date, vehicle mileage and the results of the fuel tank inspection.  

PRESSURE RELIEF - FUEL RAIL TUNING ADJUSTMENT 

Special Tool(s) 

Fig. 53: Identifying Special Tools 
Courtesy of FORD MOTOR CO. 

WARNING:

Certain steps in this procedure require the vehicle to be running, in gear 
and the engine accelerated. Be sure that the parking brake is fully set and 
the wheels are correctly chocked. Take all necessary precautions to avoid 
injury and property or equipment damage.

WARNING:

The alternative fuel (CNG or LPG) lines and components are pressurized. 

 

2003 Ford Pickup F150 

2003 GENERAL INFORMATION Fuel System-General Information-Bi-Fuel - F150 Pickup

  

1. Place the vehicle in an appropriate service bay, set the parking brake, and correctly place wheel chocks 

both in front of and behind the front wheels. Connect the exhaust to a vacuum exhaust system and 
provide adequate ventilation.  

2. Select the OFF position of the ignition switch, and the ALT position of the ALT fuel selection switch.  

3. Connect the vacuum/pressure tester, tool # 164-R0253 or equivalent, to an appropriate source of intake 

manifold vacuum.  

4. Connect the New Generation STAR (NGS) Tester, tool # 418-F048 or equivalent, to the vehicle 

diagnostic data link connector (DLC). Turn the ignition switch to the ON position. Select, monitor, and 
record powertrain control module (PCM) data PIDs ECT, O2S11, and O2S21.  

5. Start and run the engine while monitoring the PCM PID ECT. Allow the engine to warm up until the 

PCM PID ECT indicates 190 degrees F. 

6. Select, monitor, and record the alternative fuel control module (AFCM) PID MAP and vacuum. Place the 

transmission gear in reverse while applying the brake pedal then slowly apply pressure to the accelerator 
pedal. Continue to accelerate until the AFCM PID MAP indicates 7.3 or 7.4 PSI and record the vacuum. 
This vacuum value point will be used in the remaining procedure steps as the 'tuning point'.  

7. Allow the accelerator to return to the idle position and place the transmission gear in the park position.  

8. Locate the two adjustment screw holes on the top of the tuning tee assembly, remove any sealant and 

access the adjustment screws. 

Use care when servicing the system and take all necessary precautions to 
avoid personal injury. Always follow all applicable procedures concerning 
fuel leak testing and fuel system inspection.

WARNING:

This step requires the vehicle to be running, in gear and the engine 
accelerated. Be sure that the parking brake is fully set and the 
wheels are correctly chocked. Take all necessary precautions to 
avoid injury and property or equipment damage.

 

2003 Ford Pickup F150 

2003 GENERAL INFORMATION Fuel System-General Information-Bi-Fuel - F150 Pickup

  

Fig. 54: Locating Adjustment Screw Holes On Top Of Tuning Tee Assembly 
Courtesy of FORD MOTOR CO. 

9. Position both tuning tee adjustment screws to their 'neutral' state by turning them counterclockwise with a 

slotted screwdriver until the screw head tops are flush with the top of the tuning tee and then turning them 
clockwise two complete turns.  

10. With the engine at idle speed and the transmission gear in the park position, select the NGS GRAPH 

option. Record ten seconds of data from PCM PIDs O2S11 and O2S21 (1 and 2). Retrieve the recorded 
data and identify which of the OS2 signals displays the longest high state time (1). 

WARNING:

Never remove the tuning tee adjustment screws while the low 
pressure fuel lines are pressurized. Use caution when setting the 
adjustment screws. If the adjustment screws become dislodged 
from the tuning tee serious personal injury may result.

 

2003 Ford Pickup F150 

2003 GENERAL INFORMATION Fuel System-General Information-Bi-Fuel - F150 Pickup

  

Fig. 55: Identifying OS2 Signals 
Courtesy of FORD MOTOR CO. 

11. Use an assistant in the driver seat to repeat step 6 . Obtain and hold the 'tuning point' vacuum value.  

12. Select the NGS GRAPH option and record ten seconds of data from PCM PIDs O2S11 and O2S21. 

Allow the accelerator to return to the idle position and place the transmission gear in the park position.  

13. Retrieve the recorded data and identify which of the OS2 signals displays the longest high state time as in 

step 10.  

14. Determine which of the tuning tee adjustment screws requires adjustment. This is the only screw to be 

adjusted throughout the entire tuning tee procedure and is determined by the following: The PCM PID 
O2S11 data reflects the upstream bank 1 O2S and is adjusted with the passenger side tuning tee 
adjustment screw (1). The PCM PID O2S21 data reflects the upstream bank 2 O2S and is adjusted with 
the driver side tuning tee adjustment screw (2). To reduce the PCM PID O2S11 or O2S21 high state time 
the corresponding adjustment screw is turned clockwise and to increase the high state time the adjustment 
screw is turned counterclockwise. 

WARNING:

This step requires two people while the vehicle is running, in gear, 
and the engine accelerated. Be sure that the parking brake is fully 
set and the wheels are correctly chocked. Take all necessary 
precautions to avoid injury and property or equipment damage.

 

2003 Ford Pickup F150 

2003 GENERAL INFORMATION Fuel System-General Information-Bi-Fuel - F150 Pickup