Ford F150 Pickup. Manual - part 1601

 
Reconnect EVAP canister outlet tube. Remove plug from EVAP return tube and reconnect tube to intake 
manifold. Ensure fuel filler cap is properly installed. Turn ignition switch to ON position. Select PCM 
FTP V and EVAPPDC PIDs from PID/DATA MONITOR & RECORD menu. Start engine and allow to 
idle. When EVAPPDC PID is zero, FTP V PID should be less than 2.40 volts. If PCM PID values are as 
specified, replace EVAP canister purge valve. Perform EVAPORATIVE EMISSIONS SYSTEM 
LEAK TEST. If EVAP system passes leak test, perform EVAPORATIVE EMISSION REPAIR 
VERIFICATION DRIVE CYCLE. If PCM PID values are not as specified, perform EVAPORATIVE 
EMISSIONS SYSTEM LEAK TEST. If EVAP system passes leak test, perform EVAPORATIVE 
EMISSION REPAIR VERIFICATION DRIVE CYCLE. 

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline

  

2003 ENGINE PERFORMANCE

Trouble Shooting - No Codes - Bi-Fuel - Gasoline/CNG 

INTRODUCTION 

This article contains bi-fuel system trouble shooting tests only. For gasoline or flex-fuel vehicles with EEC-V 
systems, see TROUBLE SHOOTING - NO CODES - CNG, FLEX-FUEL & GASOLINE article. Always 
retrieve Powertrain Control Module (PCM) DTCs before Alternate Fuel Control Module (AFCM) DTCs. If any 
network "U" type DTCs are present, repair prior to PCM DTCs. If PCM DTCs are retrieved, go to 
DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & 
GASOLINE article and service DTCs as necessary. If AFCM DTCs are retrieved, go to DIAGNOSTIC 
TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - BI-FUEL - GASOLINE/CNG article. If no 
DTCs are present, perform SYMPTOM DIAGNOSIS under SYMPTOMS to diagnose driveability problems 
existing when a hard fault code is not present. If all symptom tests check okay, perform INTERMITTENT 
PROBLEM DIAGNOSIS under INTERMITTENTS. 

For specific system or component testing procedures, see SYSTEM & COMPONENT TESTING - BI-FUEL 
GASOLINE/CNG article. For specifications, see ON-VEHICLE ADJUSTMENTS - TRUCKS article or 
appropriate SERVICE & ADJUSTMENT SPECIFICATIONS article. 

PRELIMINARY CHECKS 

Check for vacuum leaks. Check air intake duct and air filter. Check ignition wiring. Check alternate fuel tank(s) 
for adequate CNG level. Check wiring harness connector for poor connections. Check PCM, AFCM, sensors 
and actuators for damage. Check engine coolant for proper level and mixture. Check A/T fluid for proper level 
and quality. Make all repairs before performing SYMPTOM DIAGNOSIS . 

SYMPTOMS 

NOTE:

Some driveability problems may have been corrected by manufacturer with a 
revised computer calibration chip or computer control unit. Check with 
manufacturer for latest chip or computer application.

NOTE:

Bi-fuel systems operating in Alternate (ALT) fuel mode (CNG) are gaseous-type 
fuel systems that require a higher spark plug firing voltage to ignite fuel and 
puts a higher load on vehicle ignition system. A secondary ignition system may 
not operate well or may exhibit problems when running on alternate fuel; such 
as backfiring or stalling, even though no problems exist while running on 
gasoline.

CAUTION: When battery is disconnected, vehicle computer may lose memory data. 

Driveability problems may exist until computer systems have completed a 
relearn cycle. Before disconnecting battery, see COMPUTER RELEARN 
PROCEDURES article in GENERAL INFORMATION.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Trouble Shooting - No Codes - Bi-Fuel - Gasoline/CNG

  

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Trouble Shooting - No Codes - Bi-Fuel - Gasoline/CNG

  

SYMPTOM DIAGNOSIS 

Symptom checks cannot be used properly unless problem occurs while vehicle is being tested. To reduce 
diagnostic time, retrieve Powertrain Control Module (PCM) and Alternate Fuel Control Module (AFCM) 
DTCs. Ensure QUICK TEST in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article or 
QUICK TEST in SELF-DIAGNOSTICS - BI-FUEL - GASOLINE/CNG article is performed before 
diagnosing a symptom. The following symptoms are available for diagnosis:  

z

ROUGH OR ROLLING IDLE, STALLS, MISSES, HESITATION OR SURGE  

z

HARD START OR LONG CRANK  

z

NO START/NORMAL CRANK - ALT FUEL MODE  

z

NO START/NORMAL CRANK - GASOLINE MODE  

z

SLOW RETURN TO IDLE  

z

FAST IDLE (DIESELS/RUNS ON)  

z

LOW IDLE (STALLS ON DECELERATION)  

z

BACKFIRES  

z

LACK/LOSS OF POWER  

z

SPARK KNOCK  

z

POOR FUEL ECONOMY  

z

VEHICLE FAILS EMISSIONS/EMISSIONS COMPLIANCE  

z

ALT FUEL SWITCH/INDICATOR OPERATION  

ROUGH OR ROLLING IDLE, STALLS, MISSES, HESITATION OR SURGE 

z

Check fuel delivery system. See TEST HC: FUEL DELIVERY SYSTEM under SYSTEM TESTS in 
SELF-DIAGNOSTICS - BI-FUEL - GASOLINE/CNG article.  

z

Check secondary ignition system. See TEST JB: SECONDARY IGNITION under SYSTEM TESTS in 
SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article.  

z

Check exhaust system for restriction. See TEST HF: CATALYST EFFICIENCY MONITOR & 
EXHAUST SYSTEMS under SYSTEM TESTS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & 
GASOLINE article.  

z

Check PCV system. See TEST HG: PCV SYSTEM under SYSTEM TESTS in SELF-DIAGNOSTICS -

NOTE:

Check vehicle for any driveability symptoms in gasoline mode. Repair any 
driveability symptoms in gasoline mode before diagnosing ALT fuel system. Go 
to SYMPTOM DIAGNOSIS under SYMPTOMS in TROUBLE SHOOTING - NO 
CODES - CNG, FLEX-FUEL & GASOLINE article.

NOTE:

If engine stalls after start up and base gasoline engine system has sufficient 
fuel, diagnose for a no-start. Go to TEST AC: NO START/HARD START IN ALT 
FUEL - ALT FUEL SWITCH INDICATOR IS ON, THEN OFF under SYSTEM TESTS 
in SELF-DIAGNOSTICS - BI-FUEL - GASOLINE/CNG article.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Trouble Shooting - No Codes - Bi-Fuel - Gasoline/CNG

  

CNG, FLEX-FUEL & GASOLINE article. 

z

Check automatic transmission operation. See appropriate DIAGNOSIS article in AUTOMATIC 
TRANSMISSIONS.  

z

Check EVAP emission system for blockages (engine stalls) or leaks (excessive fuel odor). See SYSTEM 
TESTS (EVAPORATIVE EMISSION) in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE 
article.  

z

Check engine mechanical condition. Check compression, camshaft, valve train components, etc. Repair 
as necessary. See appropriate article in ENGINES.  

z

Check air intake system. See TEST HU: AIR INTAKE SYSTEM under SYSTEM TESTS in SELF-
DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article.  

z

Check Mass Air Flow (MAF) sensor and related circuits. See TEST DC: MASS AIRFLOW SENSOR 
under SYSTEM TESTS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article. 

z

Additional Checks 
 
Check for correct PCM Vehicle Identification (VID) block information. See FLASH ELECTRICALLY 
ERASEABLE PROGRAMMABLE READ ONLY MEMORY (FLASH EEPROM) under 
PROGRAMMING PCM in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article. Check 
drivelines. Check charging system. See appropriate GENERATORS & REGULATORS article in 
ELECTRICAL. Check traction control system (if equipped). See appropriate ANTI-LOCK article in 
BRAKES. Check A/C system for surge with A/C on, and check A/C compressor diode, if equipped, for 
rolling idle. See appropriate AUTOMATIC or MANUAL A/C-HEATER SYSTEMS article in HVAC. 
Check speed control system for surge with speed control on. See appropriate CRUISE CONTROL 
SYSTEMS article in ACCESSORIES & EQUIPMENT. Ensure engine RPM/speed limiting functions of 
PCM are operating properly. Check for incorrect high vehicle speed signal. If no problems are indicated, 
return to SYMPTOM DIAGNOSIS to identify any additional symptoms or check for intermittent faults. 
See TEST Z: INTERMITTENT under SYSTEM TESTS in SELF-DIAGNOSTICS - CNG, FLEX-
FUEL & GASOLINE article.  

HARD START OR LONG CRANK 

z

Check battery condition and amperage draw. See appropriate GENERATORS & REGULATORS article 
in ELECTRICAL.  

z

Check secondary ignition system. See TEST JB: SECONDARY IGNITION under SYSTEM TESTS in 
SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article.  

z

Check fuel delivery system. See TEST HC: FUEL DELIVERY SYSTEM under SYSTEM TESTS in 
SELF-DIAGNOSTICS - BI-FUEL - GASOLINE/CNG article.  

z

Check air intake system. See TEST HU: AIR INTAKE SYSTEM under SYSTEM TESTS in SELF-
DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article.  

z

Check exhaust system for restriction. See TEST HF: CATALYST EFFICIENCY MONITOR & 

NOTE:

Alternate fuel engine cranking time is normally longer than gasoline engine 
cranking time. Check vehicle for add-on anti-theft devices that may disable 
starting system. If equipped, disable system before continuing.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Trouble Shooting - No Codes - Bi-Fuel - Gasoline/CNG