Envoy, Rainer, Trailblazer 2006-2007

Fuel Tank Pressure (Ftp) Sensor

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Operation



The Fuel Tank Pressure (FTP) sensor measures the difference between the pressure or vacuum in the fuel tank and outside air pressure. The control module provides a 5V reference and a ground to the FTP sensor. The FTP sensor provides a signal voltage back to the control module that can vary between 0.1-4.9 volts. As FTP increases, FTP sensor voltage decreases, high pressure equal low voltage. As FTP decreases, FTP voltage increases, low pressure or vacuum equal high voltage.

Removal & Installation



  1. Disconnect the negative battery cable.
  2.  
  3. Remove the fuel tank.
  4.  
  5. Disconnect the fuel tank pressure harness connector.
  6.  
  7. Remove the Fuel Tank Pressure (FTP) sensor.

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    Fig. Removal of the Fuel Tank Pressure (FTP) sensor

  8.  

To install:

  1. Install the new FTP seal.
  2.  
  3. Install the fuel tank pressure sensor.
  4.  
  5. Connect the fuel tank sensor harness connector.
  6.  
  7. Install the fuel tank.
  8.  
  9. Connect the negative battery cable.
  10.  

Testing




NOTE
Refer to the J-41413-200 operation manual for detailed instructions.

  1. Inspect the EVAP vent system for a restriction.
  2.  
  3. Test the low reference circuit of the FTP sensor for an open or for high resistance.
  4.  
  5. With the GE-41415-50, connect the J-41413-200 to the fuel filler neck.
  6.  
  7. Start the engine.
  8.  
  9. Allow the engine to idle.
  10.  
  11. Use the Purge/Seal function to seal the system with a scan tool.
  12.  
  13. Command the EVAP canister purge solenoid valve to 20 percent.
  14.  
  15. Observe the vacuum/pressure gage on the J-41413-200 and the FTP parameter on the scan tool.
  16.  
  17. Allow the vacuum to increase on the gage of the J-41413-200 until it reaches approximately 16 inches H2O, or until the vacuum reached the abort limit on the scan tool.
  18.  
  19. If the difference between the FTP parameter on a scan tool and the vacuum/pressure gage on the J-41413-200 was more than 1 inch, replace the FTP sensor.
  20.  
  21. If the maximum Fuel Tank Pressure Sensor parameter on a scan tool display was less than 3.2 volts, replace the FTP sensor.
  22.