whooshing sound when removing gas cap

What has not been breached here - and should have been long
ago - is if the owner was in the habit of topping off when gassing
up at the station: 'click-thunk', 'click-thunk'. That action could
contribute to his 'whooshing' experience.
Reply to
thekmanrocks
I hear no whooshing sounds and I always do three topoff click-thunks -- even then I don't approach spillage level.
Reply to
The Real Bev
On anything newer than 2000 that is a good way to wipe out the charcoal canister. Fuel goes down the vent line attached to the side of the fill pipe and drowns the canister.
Reply to
Steve W.
From what I read, that closes when fuel gets high enough in the neck, right? I would assume that it's located to prevent overflow...
What actually makes the nozzle shut off? Upon occasion I've put in at least another gallon after the first automatic click-thunk shutoff. I like to fill it as full as possible -- you never can tell when you'll just be able to make it to the Mesquite station on fumes because it was too hard to find a cheap gas station in Vegas.
Reply to
The Real Bev
"newer than 2000 that is a good way to wipe out the charcoal canister. Fuel goes down the vent line attached to the side of the fill pipe and drowns the canister. "
^This!!^ Why I haven't topped off in fifteen years!
Of course, you might as well be explaining it to a wall - present "Real" company notwithstanding.
Reply to
thekmanrocks
No the flap I'm talking about is the one the fuel fill nozzle opens just below the cap. That stays open while filling to allow vapor to pass the pump nozzle. It acts as a valve to keep debris out as well as a restriction to keep people from using the wrong pump to fill the tank (diesel usually has a larger nozzle diameter that won't fit) Plus it helps prevent the fuel from pouring out at the instant the nozzle trips off.
The nozzle shuts off when it detects a change in vacuum inside the handle. If you look inside a nozzle you will see a small hole or tube inside. While filling the gas flow over the hole/tube creates a vacuum. While gas is flowing that vacuum doesn't do much. However as soon as the tank is full the gas backs up in the fill neck. That blocks the tube/hole and the instant lack of vacuum trips a small diaphragm inside the filler handle which stops the fuel.
Reply to
Steve W.
I first saw those when unleaded became the only option (remember smog heads?) and thought it was just to restrict the size of the nozzle that could be inserted.
Given my sinful triple-top-up procedure, I've observed that different pumps have different levels of stoppage. Is there an actual standard?
Reply to
The Real Bev
Most of the time the "standard" is simply that it shuts off before it sprays you with fuel. It all depends on the flow rate from the pump and how well the fuel tank accepts high flow of fuel. Get a real fast pump and try feeding some of the imports where the fuel neck is just a hair larger than a garden hose and it can be interesting. Most vehicles have multiple restrictions in the filler neck and tank as well. Things like a screen to prevent siphoning or the rollover ball in the top of the tank or the vapor vent from the tank being small.
Reply to
Steve W.

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