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View Full Version : What happens if you remove the gas cap?


Giga Shadow
04-29-2004, 11:40 PM
That sucking noise when you uncap the filler neck...

How does it effect th car's performence?
What if you run with no gas cap... :?:

Will there be some sort of vaccum leak?
Is that just for smog?

ec437
04-30-2004, 12:47 AM
The sucking noise is because as you suck gas out of the tank, the volume of the air in the tank increases but the amount of air stays the same. Therefore you get a sucking sound because of the low pressure in the tank when you uncap it to refill. Running without a cap would not affect the car's performance at all, negatively or otherwise.