Buzzing vacuum cut valve and excessive gas vapor

[merope]

Hi All,

I am new to the forum with an 04 Pathfinder, which I got a year ago. Last summer the vacuum cut valve (not the electronic bypass valve) started buzzing. I could only identify it after the engine was shut off, but it may be doing it while it is running. I didn't fix it, and it stopped doing it during the winter. Now that the temperatures are rising (I live in Arizona), it started doing it again and I noticed excessive fuel vapor coming out of the water separator hose at the end of the car. I am wondering, whether that is a result of a possibly faulty vacuum cut valve or whether I have multiple problems on my hand and if the buzzing I hear is a problem at all. I assume so, no car should be buzzing once shut off.

Any feedback welcome.

Thanks

[merope]

Well, I removed the vacuum cut valve and the vacuum cut bypass valves. The vacuum cut valve seems to pass its tests. The top of it is snapped on and loose, so I guess that gave the buzzing sound. That also means that some air must have passed through it after shutoff to generate the sound.

The bypass valve also seems to be shut. I didn't power it to see that it opens, but I assume it does, since I am not getting any engine codes. My best guess is that when the car is hot, the bypass valve opens slightly, allowing fuel to vapor into the canister. When idling, it is not purged, therefore it comes out of the water separator. I ordered new parts (both valves), which will be here in 2 days. I hope this solves the problem. Other than having issues with the refueling valve, I don't see any other way that fuel could have ended up in the EVAP canister. Since I have the buzzing sound, a faulty bypass valve is my best guess.