Question: Is the gas tank for the C4 vented? Mine doesn't seem to be.

[tcannon]

My new-to-me C4 sure seems to not have a vented tank, or vented cap. When I take the cap off to fill up it sounds like a zombie desperately gasping for a breath as I unscrew the cap. It sure doesn't seem normal to me but the guy I bought the car from was of the opinion that all C4's are like that. I'm curious what the fuel pump's opinion might be as I'm sure it's working overtime.

It's an aftermarket locking cap and I couldn't guess the age but I found the keys for the cap back behind one of the seats and they were nearly covered over with rust so I am certain the PO wasn't the guy who purchased it -- the keys look about the same age as the guy I bought the car from.

Do I have a tank vent that is clogged? I am putting a vented cap on regardless which is a fine interim fix but I'm wondering if there's a vent to clean or a tube that might be kinked and where it might be ... if there's a vent at all.

Thanks!

Thomas

 

[Otter]

My new-to-me C4 sure seems to not have a vented tank, or vented cap. When I take the cap off to fill up it sounds like a zombie desperately gasping for a breath as I unscrew the cap. It sure doesn't seem normal to me but the guy I bought the car from was of the opinion that all C4's are like that. I'm curious what the fuel pump's opinion might be as I'm sure it's working overtime.

It's an aftermarket locking cap and I couldn't guess the age but I found the keys for the cap back behind one of the seats and they were nearly covered over with rust so I am certain the PO wasn't the guy who purchased it -- the keys look about the same age as the guy I bought the car from.

Do I have a tank vent that is clogged? I am putting a vented cap on regardless which is a fine interim fix but I'm wondering if there's a vent to clean or a tube that might be kinked and where it might be ... if there's a vent at all.

Thanks!

Thomas

Not vented as far as I know. When working on fuel rails, injectors or system, ALWAYS remove/crack the gas cap, otherwise fuel will try(and be successful) to escape.

 

[Vettehead Mikey]

No car of any type has had a vented tank or cap since the early '70s, when EVAP systems first appeared.

 

[LLC5]

My new-to-me C4 sure seems to not have a vented tank, or vented cap. When I take the cap off to fill up it sounds like a zombie desperately gasping for a breath as I unscrew the cap. It sure doesn't seem normal to me but the guy I bought the car from was of the opinion that all C4's are like that. I'm curious what the fuel pump's opinion might be as I'm sure it's working overtime.

It's an aftermarket locking cap and I couldn't guess the age but I found the keys for the cap back behind one of the seats and they were nearly covered over with rust so I am certain the PO wasn't the guy who purchased it -- the keys look about the same age as the guy I bought the car from.

Do I have a tank vent that is clogged? I am putting a vented cap on regardless which is a fine interim fix but I'm wondering if there's a vent to clean or a tube that might be kinked and where it might be ... if there's a vent at all.

Thanks!

Thomas

Your vehicle came from the factory with a sealed gas cap and a charcoal canister per federal emission standards.

 

[DonB]

The gush of air you hear is NORMAL. It does NOT affect the fuel draw capabilities of the fuel pump what so ever. The fuel pump is submerged in the fuel tank and is quite powerful. The EVAPorative system draws gas fumes, from the tank, through a small steel line that runs from the top left of the tank and snakes it's way up along the left frame rail (with the brake lines) to the canister(which on my '90) is located in the left front corner. There are various vacuum hoses and control solenoids (depending on year and model) connecting the canister to intake manifold vacuum that feed the gas fumes into the engine to be burned and disposed of. This keeps them from being expelled into the environment.

You are (probably) violating the law putting a vented cap on the tank and in some cases you may trigger a fault code and the dreaded "Check Engine" light.

Do yourself a favor and go to a parts store and get the correct cap for the car.

The best way to "take care" of your fuel pump is to NOT drive around with less than a 1/4 tank of fuel. The fuel sloshing around in the tank actually cools the pump. Thus keeping a good amount of fuel adds to the longevity of the pump. I'd also put a bottle of Techron in the tank once a year too. It keeps the fuel system "Happy."