LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Pontiac >> 2003 >> Vibe Base, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - System & Component Testing >> Fuel Systems >> Fuel Injector Balance Test With Special Tool >> Diagnostic Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnostic Procedure

  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 1.8L VIBE article.
  2. Was the Fuel Injector Coil Test Procedure performed? If yes, go to next step. If no, go to FUEL INJECTOR COIL TEST - ENGINE COOLANT TEMPERATURE BETWEEN 50-95°F (10-35°C)  .
  3. Is the engine coolant temperature more than 201°F (94°C)? If yes, go to next step. If no, go to step  5 .
  4. Allow the engine to cool to less than the specified value. Is the engine coolant temperature less than 201°F (94°C)? If yes, go to next step.
    5. CAUTION: Wrap a shop towel around the fuel pressure connection to reduce the risk of fire and personal injury. The towel will absorb any fuel leakage that occurs during the connection of the fuel pressure gauge. Place the towel in an approved container when the connection of the fuel pressure gauge is complete.
  5. Install a fuel pressure gauge. See FUEL GAUGE under FUEL SYSTEMS in REMOVAL & INSTALLATION - VIBE article. Energize the fuel pump using the scan tool. Place the bleed hose of the fuel pressure gauge into an approved gasoline container. Bleed the air out of the fuel pressure gauge. Observe the reading on fuel pressure gauge. Is the fuel pressure 44-50 psi (301-347 kPa)? If yes, go to next step. If no, go to FUEL SYSTEM DIAGNOSIS  .
  6. Turn the fuel pump OFF. Does the fuel pressure remain constant? If yes, go to next step. If no, go to FUEL SYSTEM DIAGNOSIS  .
  7. Use 2 jumper wires from the Connector Test Adapter Kit (J 35616-A), or equivalent, to connect the fuel injector to the Fuel Injector Tester test leads (J 39021). Connect test leads to battery voltage and ground. Set the amperage supply selector switch on the fuel injector tester to the Balance Test 0.5-2.5 amp position. Energize fuel pump using the scan tool. Record fuel pressure indicated by the fuel pressure gauge after the fuel pressure stabilizes. This is the 1st pressure reading. Energize the fuel injector by depressing the PUSH TO START TEST button on the fuel injector tester. Record the fuel pressure indicated by the fuel pressure gauge after the fuel pressure gauge needle has stopped moving. This is the 2nd pressure reading. Repeat procedure for each fuel injector. Subtract the 2nd pressure reading from the 1st pressure reading for one fuel injector. The result is the pressure drop value. Obtain a pressure drop value for each fuel injector. Add all of the individual pressure drop values. This is the total pressure drop. Divide the total pressure drop by the number of fuel injectors. This is the average pressure drop. Does any fuel injector have a pressure drop value that is higher or lower than the average pressure drop by 1.5 psi (10 kPa)? If yes, go to next step. If no, go to SYMPTOMS - ENGINE CONTROLS under SYMPTOMS in TROUBLE SHOOTING - NO CODES - 1.8L VIBE article.
    8. NOTE: Do not repeat any portion of this test before running the engine to prevent the engine from flooding.
  8. Re-test any fuel injector that does not meet 1.5 psi (10 kPa). Refer to the procedure in step 7)  . Does any fuel injector still have a pressure drop value that is either higher or lower than the average pressure drop by 1.5 psi (10 kPa)? If yes, go to next step. If no, go to SYMPTOMS - ENGINE CONTROLS under SYMPTOMS in TROUBLE SHOOTING - NO CODES - 1.8L VIBE article.
  9. Replace the fuel injector(s). After repair, go to next step.
  10. Does an engine performance concern still exist? If yes, go to SYMPTOMS - ENGINE CONTROLS under SYMPTOMS in TROUBLE SHOOTING - NO CODES - 1.8L VIBE article. If no, system is okay at this time.
scientia non olet · About LEMON Manuals