How fix po446 evaporative emission system vent contril circuit if can't how much on 2002 Toyota Tacoma

Did tune up 800 miles ago including file filter I have 141680 miles it stalls at gas pump, no leaks on hose but still runs good

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2 answers
I'm assuming you mean fuel filter(file filter). Not quite understanding what you mean by "stalls at gas pump". I think you mean you are having difficulty refueling.

Customer Concern: Check engine light is on with code P0446. On the early evaporative systems, this code is for a leak in the charcoal canister.
Tests/Procedures: 1. Verify the 3-way Vacuum Switching Valve (VSV) on the canister operates correctly. When the VSV is not grounded, the Fuel Tank Pressure (FTP) sensor should be connected to the canister side of the system only. When the VSV is grounded, then the FTP sensor should monitor only the fuel tank.

2. Monitor the FTP and unplug the 3-way VSV and draw a vacuum into the canister and verify it will hold vacuum and the pressure sensor voltage will decrease .

3. Test and verify the purge solenoid and wire harness are all OK. The purge solenoid should apply vacuum to the charcoal canister when grounded. Also, verify the hose from the purge solenoid to the charcoal canister does not leak.
Tech Tips: It is common for the 3-way VSV to stick or not operate correctly or the charcoal canister to be faulty. The charcoal canister has many check valves and springs built inside, so always replace the canister and 3-way VSV as a assembly so the code does not reset.
Also make sure all vacuum hoses are attached around the area of the air filter housing, it's easy for the hoses to become dislodged when changing the air filter.