GM Service Manual Online
For 1990-2009 cars only
Table 1: Fuel System

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 P0171, 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 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 EVAP system for the following:

    •  (EVAP) System for excess fuel in the EVAP lines and/or in the EVAP canister. Refer to Evaporative Emissions Hose Routing Diagram .
    • EVAP system for integrity. Refer to System Testing in DTC P0442 .

Poor Fuel Quality

Problem

Causes

Definition: During the fueling process a continual, occasional, or no fuel nozzle shut-off condition has occurred.

Difficult to fill

    • Fill limiter vent valve stuck closed
    • Evaporative emission (EVAP) canister restricted
    • EVAP vent valve stuck closed
    • Restricted vapor lines
    • High Reid vapor pressure or high fuel temperature
    • Fuel filler hose is pinched or kinked
    • Ignition switch ON. Vent Valve Closed

Over fill

    • Pressure relief valve stuck open or leaking
    • Fill limiter vent stuck open or leaking

Premature shut off of the fuel dispensing nozzle

    • Fill limiter vent valve stuck closed
    • EVAP canister restricted
    • EVAP vent valve stuck closed
    • Restricted vapor lines
    • High Reid vapor pressure or high fuel temperature
    • Ignition switch ON, EVAP vent valve closed

Fuel spitback

    • Restricted EVAP canister
    • High Reid vapor pressure or high fuel temperature
    • Ignition switch ON, EVAP vent valve closed