New guy with Fuel Fill issue

[DASHAWN1234]

so should i change the fuel filler neck....and does anyone have info on how to change it?

[DASHAWN1234]

so you are saying that fuel tank pressure sensor is just a switch? and does anyone know how to change the filler neck?

[Archon]

As the FTP sensor measures the amount of vacuum, as well as the decay rate, I think it is more than just just an "on/off" switch. If you're not getting a reading from it, you may want to check for proper voltage (I believe 5v) to it. If that is proper, then replacing the sensor may help. This is a description of the various tests that the system does.

The EVAP diagnostic tests include the following tests:

Weak Vacuum Test: This tests for large leaks and blockages in the EVAP system. The FTP sensor detects low fuel tank pressure resulting from a large vacuum leak or a restriction in the vacuum supply to the fuel tank. The FTP sensor value should increase over a period of time. If the PCM does not detect in increase, a malfunction is indicated by setting DTC P0440.

Weak Vacuum Follow-up Test: This tests the EVAP system after the Weak Vacuum Test has failed. The FTP sensor looks for high tank vacuum over a period of time. If this occurs. the Weak Vacuum Test will Pass. If Weak Vacuum does not pass, the test continues through this ignition cycle.

Vacuum Decay Test: This tests for small leaks in the EVAP system. The decay rate is determined by measuring the change in fuel tank pressure (vacuum) over a period of time. If the decay rate is greater than a calibrated value, than another vacuum decay test will be initiated. If vacuum decay is still greater than a calibrated value, a malfunction is indicated by setting DTC P0442.

Fuel Vapor Build Pressure Test: This test is used to determine the vacuum leak size. When the vacuum has decayed to near zero, the PCM subtracts measured sloap from the vacuum decay to calculate to predict leak size. If the calculation indicates that a leak is present, the small leak test will fail.

Canister Vent Restriction Test: This tests for a restriction in the EVAP vent system. The FTP sensor looks for sufficient vacuum from the engine intake manifold. After a period of time and conditions have been met, then this test will pass. If the vacuum value is to high, a malfunction is indicated by setting a DTC P0446.

Purge Valve Leak Test: This tests for small leaks to the intake manifold. This is accomplished by sealing the EVAP system purge valve and vent valve, and allowing the PCM to monitor the FTP sensor. The FTP sensor value should not increase. If the PCM detects an increase, a malfunction is indicated by setting DTC P1441.

[DASHAWN1234]

thanks a lot the info is helpful...now i know what direction to head in...because after i changed the gas cap twice my gas cap doesn't hold any pressure..for example if i twist my gas cap until it clicks three times or more i can just barely touch it and it will come right off... thats why i thought to change the filler neck at first