GM Service Manual Online
For 1990-2009 cars only

Fuel System

Symptoms

Fuel System

Find the symptom in the left column and perform the test/inspection procedure in the right column, be sure to review each cell of the table to identify all tests for a symptom.

    • Hard Start
    • Surges/Chuggles
    • Lack of Power, Sluggishness, or Sponginess
    • Detonation/Spark Knock
    • Hesitation, Sag, Stumble
    • Cuts Out, Misses
    • Poor Fuel Economy
    • Rough, Unstable, or Incorrect Idle and Stalling
    • Backfire
    • Test the fuel system for correct operation, restriction, volume, and pressure. Refer to Fuel Pump Electrical Circuit Diagnosis and Fuel System Diagnosis .
    • Inspect for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Inspect the throttle body for coking.
    • Inspect for lean or rich conditions. Refer to DTC P0171 or P0172 , Conditions for Running the DTC.

Dieseling/Run On

Test the fuel system for excessive fuel pressure. Refer to Fuel System Diagnosis .

    • Hard Start
    • Surges/Chuggles
    • Lack of Power, Sluggishness, or Sponginess
    • Detonation/Spark Knock
    • Hesitation, Sag, Stumble
    • Cuts Out, Misses
    • Poor Fuel Economy
    • Rough, Unstable, or Incorrect Idle and Stalling
    • Dieseling, Run-On

Test for proper operation of the fuel injectors. Refer to the Fuel Injector Diagnosis .

    • Surges/Chuggles
    • Lack of Power, Sluggishness, or Sponginess
    • Hesitation, Sag, Stumble
    • Cuts Out, Misses
    • Rough, Unstable, or Incorrect Idle and Stalling

Inspect the evaporative emission (EVAP) system for the following:

    •  EVAP System for excess fuel in the EVAP lines and/or in the EVAP canister
    • EVAP system for integrity--Refer to DTC P0442 .