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Home >> Isuzu >> 2000 >> Trooper S, 4WD, Part Time >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 3.2L & 3.5L >> Diagnostic Trouble Code Identification >> DTC P1171: Fuel System Lean During Acceleration >> Diagnostic Procedure
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Diagnostic Procedure

  1. Perform On-Board Diagnostic (OBD) System Check. See BASIC DIAGNOSTIC PROCEDURES article. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
  2. If any other component-related DTCs are set, diagnose them first. If no other DTC is present, go to next step.
  3. Check fuel level. Add fuel if tank is almost empty. If fuel was added, go to next step. If no additional fuel was required, go to step  5.
  4. Start vehicle and bring engine to normal operating temperature. Raise engine speed to 1200 RPM. Using scan tool, observe HO2S-1 voltage. If scan tool reading toggles between .1-.9 volt and voltage increases to high end of specification when throttle is opened half way for a few seconds, see FUEL SYSTEM ELECTRICAL TEST in BASIC DIAGNOSTIC PROCEDURES article. If voltage reading is not as specified, go to next step.
  5. Turn ignition off. Remove fuel pump relay and crank engine to relieve fuel pressure. Install fuel pressure gauge. Replace fuel pump relay and start engine, bring to normal operating temperature and allow it to idle. Disconnect vacuum line to fuel pressure regulator and read pressure gauge. If pressure is 41-46 psi (2.8-3.3 kg/cm2 ), see OBD II SYSTEM CHECK in BASIC DIAGNOSTICS PROCEDURE article. If pressure reading is not as specified, go to next step.
  6. Check for restricted fuel lines or filter. If problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
  7. Turn ignition off. Remove fuel pump relay. Connect fused jumper wire between fuel pump relay battery feed terminal and fuel pump fuse terminal. With fuel pressure gauge still connected, pinch off fuel return line. Do not allow fuel pressure to exceed 60 psi (4.2 kg/cm2 ). Manipulate fuel line to raise pressure to more than 46 psi (3.3 kg/cm2 ). If pressure increases to more than 46 psi (3.3 kg/cm2 ), check for an intermittent problem. See DIAGNOSTIC AIDS . If pressure does not increase to 46 psi (3.3 kg/cm2 ), go to next step.
  8. Check for faulty fuel pump, restricted fuel pump strainer, incorrect fuel pump, incorrect fuel grade or hot fuel. If any problem is found, repair as necessary. Retest system.
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