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3. CHECKING FOR AIR IN FUEL SYSTEM Start the engine. With the scan tool, compare the Fuel Pressure Setpoint with the Actual Fuel Pressure readings. NOTE: If there is air in the fuel system, the Actual Fuel Pressure will oscillate more than 100 spi above Does Actual Fuel Pressure oscillate more than 100 psi above and/or below the Fuel Pressure Setpoint? Yes >> Refer to the Service Information to purge air from the fuel system. Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING). No >> Go To 4 4. FUEL PRESSURE SOLENOID With the scan tool, compare the Fuel Pressure Setpoint with the Actual Fuel Pressure readings. NOTE: A sticking Fuel Pressure Solenoid is indicated by Actual Fuel Pressure gradually dropping below the Does Actual Fuel Pressure gradually decrease then suddenly increase (spike) above the Fuel Pressure Yes >> Replace the Fuel Pressure Solenoid in accordance with the Service Information. Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING). No >> Go To 5 5. SCAN TOOL TESTS Turn the engine off. Turn the ignition on. With the scan tool, select Engine, System Tests and perform the following tests: - Injector Fuel Correction Test. - Cylinder Balance test. - Compression Test. Were any problems found? Yes >> Diagnose and/or repair as necessary. Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING). No >> Go To 6 6. INJECTOR RETURN VOLUME TEST Refer the Service Information and perform the Injector Return Volume Test. Did the Injectors pass the Return Volume Test? Yes >> Go To 7 No >> Refer to the Service Information and replace injector(s) as necessary. Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING). 7. FUEL PRESSURE SOLENOID RETURN VOLUME TEST Refer the Service Information and perform the Fuel Pressure Solenoid Return Volume Test. Did the Fuel Pressure Solenoid pass the Return Volume Test? Yes >> Replace the Fuel Pump in accordance with the Service Information. Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING). No >> Refer to the Service Information and replace the Fuel Pressure Solenoid. Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING). 9 - 670 ENGINE DIESEL DIAG KJ |