Fuel System
- Check the fuel system circuits for proper operation. See FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.1L CENTURY, GRAND PRIX & MALIBU article.
- Check for low fuel pressure. See FUEL SYSTEM DIAGNOSIS under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.1L CENTURY, GRAND PRIX & MALIBU article.
- Check for faulty fuel injectors. See FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL , FUEL INJECTOR BALANCE TEST WITH TECH 2 and FUEL INJECTOR COIL TEST under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.1L CENTURY, GRAND PRIX & MALIBU article.
- Check for fuel contamination. See ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS W/O SPECIAL TOOL or ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS W/ SPECIAL TOOL under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.1L CENTURY, GRAND PRIX & MALIBU article.
- Check any items which may cause an engine to run rich, long term fuel trim is significantly in the negative range. See DIAGNOSTIC AIDS for DTC P0172: FUEL TRIM SYSTEM RICH under DIAGNOSTIC TESTS in SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.1L CENTURY, GRAND PRIX & MALIBU article.
- Check any items which may cause an engine to run lean, long term fuel trim is significantly in the positive range. See DIAGNOSTIC AIDS for DTC P0171: FUEL TRIM SYSTEM LEAN under DIAGNOSTIC TESTS in SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.1L CENTURY, GRAND PRIX & MALIBU article.