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.

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

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

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

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

Inspect the EVAP system for the following:

    â€¢  (EVAP) System for excess fuel in the EVAP lines and/or in the EVAP canister. Refer to Evaporative Emissions Hose Routing Diagram .
    â€¢ 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

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

Over fill

    â€¢ Pressure relief valve stuck open or leaking
    â€¢ Fill limiter vent stuck open or leaking

Premature shut off of the fuel dispensing nozzle

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

Fuel spitback

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