Ford F150 Pickup. Instruction - part 1378

Are any PCM DTCs present? If yes, for DTCs P0201 through P0208, go to step 8) . For DTCs P0301 
through P0308, go to next step. For all other DTCs, see DIAGNOSTIC TROUBLE CODE 
DEFINITIONS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article. If no, go to next 
step. 

7) Check The PCM Injector Driver Fault Pid(s) 
 

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Access the appropriate INJxF PID for the suspect fuel injector.  

Does the PID status indicate YES? If yes, go to next step. If no, see SYMPTOMS in TROUBLE 
SHOOTING - NO CODES - BI-FUEL - GASOLINE/CNG article to continue diagnosis 

8) Check The PCM Fuel Injector Driver Circuit(s) For An Open And A Short To Ground 
 

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Key off.  

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Disconnect the AFCM connector C1427.  

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Disconnect the PCM connector C175.  

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Measure the resistance between the PCM connector C175 fuel injector driver circuit, harness side 
and the AFCM connector C1427 injector driver circuit, harness side; and between the PCM 
connector C175 fuel injector driver circuit, harness side and ground. See PCM CONTROLLED 
INJECTOR DRIVER PINS table under DIAGNOSTIC AIDS in TEST AA. See CONNECTOR 
IDENTIFICATION .  

Is the resistance less than 5 ohms between the PCM and the AFCM; and is the resistance greater than 
10,000 ohms between the PCM and ground. If yes, go to next step. If no, repair the circuit in question. 

9) Check The PCM Fuel Injector Driver Circuit(s) For A Short To Voltage 
 

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Key on, engine off.  

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Measure the voltage between the PCM connector C175 fuel injector driver circuit, harness side and 
ground.  

Is any voltage indicated? If yes, repair the circuit in question. If no, go to next step. 

10) Check For Correct AFCM Operation 
 

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Disconnect the AFCM.  

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Check for corrosion and pushed out pins.  

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Connect the AFCM connector and make sure it is seated correctly.  

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Operate the system and verify the concern is still present.  

Is the concern still present? If yes, install a new AFCM. If no, the system is operating correctly at this 
time. Concern may have been caused by a loose or corroded connector. 

TEST HC: FUEL DELIVERY SYSTEM 

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Self-Diagnostics - Bi-Fuel - Gasoline/CNG

  

Diagnostic Aids 

Enter this test only when all steps under QUICK TEST have been successfully completed and engine still does 
not start or if directed here from another test or chart. This test is only intended to diagnose:  

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Fuel Pressure Regulator  

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Fuel Filter  

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Fuel Supply Lines  

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Fuel Injectors  

System Inspection 

1. Visually inspect the components of the fuel delivery system. 

Mechanical 

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Loose, leaking, collapsed, kinked, or damaged fuel or vacuum lines.  

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Leaking fuel injectors.  

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Adverse driveability symptoms, such as rough idle, hard to start, misses, surges, hesitates, 
backfires.  

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Insufficient fuel in fuel tank.  

Electrical 

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Discharged battery.  

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Damaged connectors.  

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Damaged insulation.  

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Damaged components in the fuel system.  

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Blown fuse.  

2. Inspect the wiring and connectors for the solenoids and other electrical components for obvious problems 

due to looseness, corrosion, or other damage.  

3. If a component is suspected as the obvious cause of a fault, correct the cause before proceeding to the 

next step.  

4. If all system inspection checks are okay, proceed to TESTING.  

Pressure Relief - Natural Gas Bi-Fuel System 

WARNING:

Do not modify the system configuration or components. Do not install 
components not specifically designed for use with natural gas. Ford 
Motor Company has specifically designed the materials, components and 
system configuration for the 5.4L F-Series Bi-Fuel vehicle, and each 
particular system is precisely calibrated for efficient operation. The use of 
different parts or materials can produce an untested configuration that 

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Self-Diagnostics - Bi-Fuel - Gasoline/CNG

  

1. Raise the vehicle on the hoist.  

2. Remove the fuel tank shield. See Fig. 24 .  

3. Disconnect the tank valve connectors. See Fig. 25 .  

4. Set the fuel selector switch to "ALT" and run the vehicle until the indicator lamp goes out. See Fig. 26 .  

5. To pressurize the system, reverse the procedure.  

Fig. 24: Removing Fuel Tank Shield 
Courtesy of FORD MOTOR CO. 

can result in fire or personal injury or cause engine damage.

WARNING:

Fuel supply lines are always pressurized. When servicing fuel related 
components, do not smoke or carry lighted tobacco or an open flame of 
any type. Flammable mixtures may be present and can ignite, resulting in 
personal injury. The natural gas fuel system is always pressurized to 95 
psi (655 kPa) downstream of the fuel pressure regulator and up to 3600 
psi (24,821 kPa) upstream of the fuel pressure regulator. Use care when 
servicing the fuel system or personal injury can occur. The fuel system 
pressure must be relieved before any component can be removed. The 
fuel tanks must be evacuated prior to tank removal. Removal of 
components without pressure relief or tank evacuation can cause natural 
gas to escape into the air and cause injury or death.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Self-Diagnostics - Bi-Fuel - Gasoline/CNG

  

Fig. 25: Locating Fuel Tank Valve Connectors 
Courtesy of FORD MOTOR CO. 

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Self-Diagnostics - Bi-Fuel - Gasoline/CNG