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 System Diagnosis and Fuel Pump Electrical Circuit Diagnosis .
    • Inspect for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Inspect the throttle body for coking. Refer to Throttle Body Cleaning .
    • Inspect for lean or rich conditions. Refer to P0171, P0172, P0173, or P0174 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 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:

    •  Excess fuel in the EVAP lines and/or in the EVAP canister--Refer to Evaporative Emissions Hose Routing Diagram .
    • Integrity--Refer to System Testing in DTC P0442 .