Keep getting P0440 code. on 2001 Chevrolet Blazer

I keep getting the 440 code. had vapor lines replaced after smoke test. light came back 3 days later. had vent valve replaced, light still came back on 2 days later. i fill up, i turn gas cap like 3 times to make sure it sealed. Please help!

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1 answer
you need another smoke test its probly in the fill neck