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Home >> Cadillac >> 2007 >> Escalade EXT >> Repair and Diagnosis >> External Pages >> Different car >> Section 52 (Engine Controls - System & Component Testing - 8.1L) >> Fuel Systems >> Fuel Injector Balance Test With Tech 2 >> Diagnostic Procedures
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Diagnostic Procedures

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2003 GMC Yukon XL, 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Suburban, and 2003 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform Diagnostic System Check - Engine Controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 8.1L AVALANCHE, SIERRA, SILVERADO, SUBURBAN & YUKON XL article. After performing Diagnostic System Check - Engine Controls, go to next step.
  2. Perform FUEL INJECTOR COIL TEST  . After performing Fuel Injector Coil Test, go to next step.
    3. NOTE: DO NOT perform this test if ECT is greater than 201°F (94°C). Ensure there is adequate fuel in fuel tank before proceeding with this diagnostic.
  3. Turn ignition and all accessories off. Install fuel pressure gauge. Turn ignition on, with engine off. Using scan tool, command fuel pump on. You may need to command the fuel pump ON a few times in order to obtain the highest possible fuel pressure. DO NOT start engine. Observe fuel pressure gauge, with fuel pump commanded ON. Is fuel pressure 55-62 psi (385-425 kPa)? If yes, go to next step. If no, diagnose fuel system.
    4. NOTE: The fuel pressure may vary slightly when fuel pump stops operating. After fuel pump stops operating, the fuel pressure should stabilize and remain constant.
  4. Observe fuel pressure gauge for one minute. Does the fuel pressure drop more than 5 psi (34 kPa)? If yes, diagnose fuel system. If no, go to next step.
    5. NOTE: Fuel pressure may rise after fuel injector stops pulsing. Record fuel pressure value immediately after fuel injector stops pulsing. DO NOT record higher fuel pressure value.
  5. Using scan tool, select Fuel Injector Balance Test function, within Special Functions menu. Select an injector to be tested. Press ENTER. This will prime fuel system. Record fuel pressure indicated by fuel pressure gauge after fuel pressure stabilizes. This is first pressure reading. Energize fuel injector by depressing PULSE INJECTOR button on scan tool. This will energize injector and decrease fuel pressure. Record fuel pressure indicated by fuel pressure gauge after fuel injector has stopped pulsing. This is second pressure reading. Press ENTER again to bring you back to Select Injector screen. Repeat this step for each fuel injector. Subtract second pressure reading from first pressure reading for one fuel injector. Result is pressure drop value. Obtain a pressure drop value for each fuel injector. Add all individual pressure drop values. This is total pressure drop. Divide total pressure drop by number of fuel injectors. This is average pressure drop. Does any fuel injector have a pressure drop value that is more than average pressure drop or less than average pressure drop by 1.5 psi (10 kPa)? If yes, go to next step. If no, go to SYMPTOMS in TROUBLE SHOOTING - NO CODES - 8.1L AVALANCHE, SILVERADO, SUBURBAN & YUKON XL article.
  6. Replace affected fuel injectors. After repairs, go to next step.
  7. Operate system in order to verify repair. Did you correct the condition? If yes, system is okay. If no, go to SYMPTOMS in TROUBLE SHOOTING - NO CODES - 8.1L AVALANCHE, SILVERADO, SUBURBAN & YUKON XL article.
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