Possible Causes & Corrections

WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Savana, 2003 Chevrolet Silverado, and 2003 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.

Check the following items:

Ensure vehicle operator is using correct starting procedure.
Check fuel pressure. See FUEL SYSTEM PRESSURE TEST underFUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 6.0L CHEVY EXPRESS, SAVANA, SIERRA & SILVERADO - BI-FUEL & CNG article.
Test for an accurate fuel indication from Fuel Tank Pressure (FTP) sensor.
Test ECT sensor for proper operation by performing the following:
1. Allow engine temperature to reach ambient air temperature by leaving the engine off for several hours or overnight for most accurate results.
2. Turn ignition on, with engine off.
3. Using scan tool, compare ECT and IAT sensors displayed temperature. The sensors should be within 5°F (3°C) of each other.
4. Replace ECT sensor or repair ECT sensor circuit if ECT is not near the expected value.
Test TP sensor for proper operation. With throttle blade at rest position, the monitored TP sensor voltage on a scan tool should be LESS than 0.85 volt. If TP sensor is not near the expected voltage check for a faulty TP sensor, faulty TP sensor circuit, a sticking throttle shaft or linkage/cable assembly.
Test for proper operation of Crankshaft Position (CKP) sensor. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 6.0L CHEVY EXPRESS & SAVANA - BI-FUEL & CNG article DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 6.0L SILVERADO & SIERRA - BI-FUEL & CNG article.
Test for proper operation of MAP sensor, if equipped. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 6.0L CHEVY EXPRESS & SAVANA - BI-FUEL & CNG article DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 6.0L SILVERADO & SIERRA - BI-FUEL & CNG article.