Air escaping fuel tank when removing gas cap

[JTinVA]

Anyone else experience this issue. Every time I go to fill up and remove gas cap air escapes.

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[Mr._Bill]

I don't notice that, but it is supposed to be a closed system to keep the vapors from escaping into the air.

 

[ShadowsPapa]

Anyone else experience this issue. Every time I go to fill up and remove gas cap air escapes.

Apparently you haven't had a new car since 1969?
Just kidding........... but the reality of it is it's a semi-sealed system.
If it's like decades passed, it's a pressure/vacuum system. It may build a slight vacuum, or a bit of pressure. These don't vent to the air. If you have a tank that's mostly empty and the weather heats up, then pressure builds in the tank.
I can't say mine does or doesn't make the sound - I've fueled my cars and trucks that operate under the pressure/vacuum systems with canisters up for so many year I tend to ignore most such things.

 

[Wolfman]

Anyone else experience this issue. Every time I go to fill up and remove gas cap air escapes.

Mine sounds like someone growling

 

[JustinLentz]

If the system doesn't have that pressure, your system will throw a code. It's designed to sound like a gremlin... sort of.

 

[SargeDiesel]

Is this the same for a diesel... at a $1 more a gallon than gas, the only sound I can hear is my bank account draining !

 

[tbaker]

During the summertime when it’s hot they will make the air pressure sound coming out of the gas cap when you take it off mine does that I have had other vehicles to do that during the summer it goes away in the when the temperatures get cooler I guess the gas tank builds some pressure because of the heat outside a gas can that you use around the house does the same thing during the summer not in the colder months

 

[ShadowsPapa]

If the system doesn't have that pressure, your system will throw a code. It's designed to sound like a gremlin... sort of.

It's a pressure/vacuum system. There isn't always pressure. If things cool down at night, you could actually run a slight vacuum, or at least no pressure.
I've driven my own several miles with the cap off (yea, decades of driving and after 50 years I finally forgot to put the cap back on!)
No codes, no nothing. It worked fine until I had a bad feeling I had forgotten something, but had no idea what.
Maybe it takes a lot of miles, but these may or may not have pressure.
Put fuel in when it's 0 degrees out, the fuel comes out of the ground at about 55 degrees, then as you drive, the fuel cools and you actually lose pressure. it's like my truck 2 days ago - 95 degrees out, it's sitting in the sun, then that night it drops to 60, the fuel (and air in the tank) cool and a vacuum is formed. Even my fuel containers in the garage will either have pressure or vacuum when I open them to use.

 

[kevman65]

Yes, the JT will fart on you when take the gas cap off.

The later on a hot, sunny day, the louder and longer the fart.

 

[ShadowsPapa]

Yes, the JT will fart on you when take the gas cap off.

The later on a hot, sunny day, the louder and longer the fart.

Popcorn farts?

 

[kevman65]

Popcorn farts?

Oh no, these are full on beer and brat farts.

 

[tbaker]

Sugar poots or the gladiator is blowing you kisses because your putting that high dollar gas in it

 

[kevman65]

The worst I ever heard were on a motorcycle, except you'd have to barely crack the cap and let it vent or you'd wear whatever gas was still in the tank.

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