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Home >> Chevrolet >> 1998 >> Prizm Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Circuit Tests >> Fuel Injector Balance Test >> Diagnosis & Repair
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Diagnosis & Repair

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in TESTS W/CODES article. After performing OBD system check, go to next step.
  2. Perform Fuel Injector Coil Test. See FUEL INJECTOR COIL TEST -ENGINE COOLANT TEMPERATURE BETWEEN 50-95°F. After performing fuel injector coil test, go to next step.
  3. If engine coolant temperature is greater than 201°F (94°C), go to next step. If engine coolant temperature is less than 201°F (94°C), go to step 5).
  4. Allow engine to cool to less than 201°F (94°C). After engine coolant temperature is less than 201°F (94°C), go to next step.
  5. Install Fuel Pressure Gauge (J-34730-1A). Using scan tool, energize fuel pump. Place fuel pressure gauge bleed hose into a container and bleed out air. Observe fuel pressure gauge. If fuel pressure is 44-50 psi (3.0-3.4 kg/cm2 ), go to next step. If fuel pressure is not 44-50 psi (3.0-3.4 kg/cm2 ), go to FUEL SYSTEM PRESSURE TEST under BASIC FUEL SYSTEM CHECKS in BASIC TESTING article.
  6. Turn fuel pump off. If fuel pressure remains constant, go to next step. If fuel pressure does not remain constant, go to FUEL SYSTEM PRESSURE TEST under BASIC FUEL SYSTEM CHECKS in BASIC TESTING article.
  7. Access fuel injector connectors as required. Install Fuel Injector Tester (J-39021) to positive battery voltage and ground. Set amperage supply selector switch on tester to BALANCE TEST 0.5-2.5 AMP position. Install fuel injector tester on fuel injector. Using scan tool, energize fuel pump. Record fuel pressure after pressure stabilizes. This is the first reading. Press PUSH TO START TEST button on tester to energize injector. Record fuel pressure after needle stops moving. This is the second reading. Repeat step 7) for each fuel injector. Subtract second pressure reading from first pressure reading. Resulting value is pressure drop value. Perform this calculation for all injectors. Add all pressure drop values together to obtain total pressure drop value. Divide total drop pressure by number of injectors to obtain average pressure drop value. If any injector pressure drop value is 1.5 psi (1.0 kg/cm2 ) greater than or less than average pressure drop value, go to next step. If any injector pressure drop value is not 1.5 psi (1.0 kg/cm2 ) greater than or less than average pressure drop value, go to TESTS W/O CODES article.
  8. Operate engine to prevent flooding. Repeat step 7) for injectors that are not as specified. If any injector pressure drop value is still 1.5 psi (1.0 kg/cm2 ) greater than or less than average pressure drop value, go to next step. If any injector pressure drop value is not 1.5 psi (1.0 kg/cm2 ) greater than or less than average pressure drop value, go to TESTS W/O CODES article.
  9. Replace faulty fuel injector(s). After replacing fuel injector, system is okay.
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