Unplug it and see if whistle stops is easiest way. It may set a code though. Just to make sure we are talking about the same item, it is in the pic with arrow pointing to it, this will go to a vacuum source. It cold also be a tank pressure sensor problem or a shutoff valve problem which I would think that a smoke test be performed on this system would or could find your problem. Also check your secondary air injection system that can be making the noise as well. Item 3 is the anti run on valve and it may leak there or in one of the hoses. See pics
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Tuesday, October 8th, 2013 AT 9:29 AM