Circuit/System Testing: Restriction

With the engine running, the EVAP canister vent solenoid valve open, and the EVAP canister purge solenoid valve commanded to 100 percent, the fuel tank vacuum should not increase to more than 12 inches H2O.

• If the fuel tank vacuum is greater than the specified value, isolate the restriction by disconnecting one component at a time while the EVAP canister purge solenoid valve is commanded to 100 percent and the vent valve is open.

FTP Sensor

1. Ignition ON and fuel cap removed, verify that the FTP sensor parameter is between 1.3-1.7 volts.
   • If the FTP sensor parameter is not within the specified range, test the FTP low reference circuit for an open or high resistance. If the circuit tests normal, replace the FTP sensor.
2. With the GE-41415-50  , connect the J 41413-200  to the fuel filler neck. See Special Tools .
3. Start the engine.
4. Allow the engine to idle.
5. Use the Purge/Seal function to seal the system with a scan tool.
6. Command the EVAP canister purge solenoid valve to 30 percent.
7. Observe the vacuum/pressure gage on the J 41413-200  and the FTP parameter on the scan tool. See Special Tools .
8. 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. See Special Tools .
   • 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. See Special Tools .
   • If the Fuel Tank Pressure Sensor parameter on a scan tool display was less than 3.2 volts, replace the FTP sensor.