“Whoosh” from gas cap and noise inside cab?

85roktoy

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Should a properly vented factory 77 tank make a whoosh sound when you remove the gas cap?

Also getting a buzzing noise inside cab coming from the area above tank where all of the vent tubes run. Will buzz about 10 seconds then quit. Happens randomly while driving. Any ideas?
 
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Ethanol evaporating. Old carbs and fuel systems not designed for it.
 

85roktoy

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2F with sniper and mechanical fuel pump. Same things occurred with factory carb.
 

hobbes

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Yes, you should get a slight whoosh removing the fuel cap as the EVAP check valve is designed to hold a slight pressure in the tank.
 

85roktoy

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Lucked up and caught the buzzing noise on video. Vehicle not running but about 5 mins after I shut it off. Trying to post it now…
 

DangerNoodle

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Skreddy

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I had a skidoo snowmobile with 1 way valves for the gas tank venting and one was bad and made that identical noise.
 

85roktoy

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No In tank pump. I’ll replace the one way valve and see if that’s the culprit.
 
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ToyotaMatt

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No In tank pump. I’ll replace the one way valve and see if that’s the culprit.


this one way valve ?


- you never mention what direction the " WHOOSH is going or coming from ?







1666572524533.png


1666572501477.png
 

85roktoy

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Yes that one Matt. Woosh sound is when taking off gas cap. Guessing pressure built up inside?
 

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