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Home >> Isuzu >> 1997 >> Trooper LS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Fuel System >> Fuel Injection >> Fuel Injector Coil Test
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Fuel Injector Coil Test

  1. Perform On-Board Diagnostics (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in BASIC TESTING article. After performing OBD system check, go to next step.
  2. Turn ignition off. Relieve fuel pressure. See FUEL SYSTEM PRESSURE RELEASE. Connect Fuel Injector Tester (J 39021-5V) to battery positive and ground, and Injector Switch Box (J 39021-90). Connect switch box to grey fuel injector harness connector located at front of EVAP canister bracket. Set amperage supply selector switch to Coil Test 0.5 amp position. Connect DVOM leads to fuel injector tester. See Fig 1 . Set DVOM to tenths scale. Observe ECT. If ECT is within 50-95 degrees (10-30 C), go to step 3). If ECT is not within specification, go to step 5.
    Fig 1: Connecting DVOM To Fuel Injector Tester
    G97A06785Courtesy of ISUZU MOTOR CO.
  3. Set injector switch box to injector No. 1. Press PUSH TO START TEST button of tester. Observe voltage reading (voltage may rise during test). Record lowest voltage observed after first second of test. Repeat procedure on all injectors. If any injector had large fluctuations in voltage that did not stabilize or voltage reading out of 5.7-6.6 volt range, go to step 4). If all within specification, go to step 7).
  4. Replace faulty fuel injector(s). See FUEL RAIL & FUEL INJECTORS in REMOVAL, OVERHAUL & INSTALLATION. Go to step 7).
  5. Set injector switch box to injector No. 1. Press Push To Start button on injector tester. Observe voltage reading (voltage may rise during test). Record lowest voltage after first second of test. Set injector switch box to next injector and repeat procedure to all injectors. If any injector had large fluctuations in voltage that did not stabilize or voltage reading above 9.5 volts, go to step 4). If all readings within specification, go to step 6).
  6. Identify highest voltage reading recorded (below 9.5). Subtract voltage, from each injector, reading of each injector from highest voltage reading recorded. If subtracted value for any injector, is greater than 0.6 volts, go to step 4). If all within specification, go to applicable FUEL INJECTOR BALANCE TEST.
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