Question about 1998 GMC Sonoma

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  • Anonymous Aug 20, 2008

    I have the same vacuum leak noise from about the same place. Only when the vehicle is running. Lasts for a couple of seconds when vehicle turned off. Does not change when engine in nutral and reved up a bit. May change a bit when put in gear and accelerating. Any thoughts?? Thanks.

  • Charles Max LeMire Aug 20, 2008

    I have the same leak sounding noise. All the controls seem to work fine. Only happens with engine running. Does not change when in neutral and engine is reved up a bit. Seems to change some when vehicle is in gear and accelerating. Any thoughts? Thanks.



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It may be the actuators that control the vents charging up on vacuum and adjusting to position, it may be a normal noise

Posted on Aug 31, 2008


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However, I would get the fuel pressure regulator checked. it has a vacum line going to the manifold. If the diaphram inside the regulator starts leaking, it will result in low fuel pressure, and fuel will leak through the vacum line into the intake manifold - eventually this fuel ignites, like a backfire, but can be much worse - the resulting explosion can crack the manifold itself (hopefully that wasn't what you heard). It's usually fairly easy to check, by pulling the vacum line off off the regulator and checking for either fuel leaking into the line, or leaking out of the vacum port on the regulator itself. Ford recommends checking for a loose vacum line connection at both ends here anyway.

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