Charcoal Cannister 72 vette
07-05-2015, 01:23 PM
#1
Instructor
Thread Starter
Charcoal Cannister 72 vette
Posted a thread a few months back regarding gas fumes from my 72 after fill up, received very good advice and fixed the problem. Well as luck would have it, developed another problem that have to believe is related or at a minimum has something to do with the previous fix. 
Had the car out yesterday and filled up, drove around for a while, put the car in the garage and about 1/2 hour later noticed strong gasoline smell, looked at gas tank, fuel lines and filters, then noticed steady gasoline drip from charcoal canister.
Took the gas cap off, and after about 10 minutes the steady drip stopped. My question is what would cause gasoline to flow to canister? Thought the valve on tank prevented gasoline from flowing to canister? Can the roll over valve/separator be bad? Checked it when had gas fume problem had no leaks or seeping. Help
Had the car out yesterday and filled up, drove around for a while, put the car in the garage and about 1/2 hour later noticed strong gasoline smell, looked at gas tank, fuel lines and filters, then noticed steady gasoline drip from charcoal canister.
Took the gas cap off, and after about 10 minutes the steady drip stopped. My question is what would cause gasoline to flow to canister? Thought the valve on tank prevented gasoline from flowing to canister? Can the roll over valve/separator be bad? Checked it when had gas fume problem had no leaks or seeping. Help
07-06-2015, 07:57 AM
#2
Team Owner
Posted a thread a few months back regarding gas fumes from my 72 after fill up, received very good advice and fixed the problem. Well as luck would have it, developed another problem that have to believe is related or at a minimum has something to do with the previous fix.
Had the car out yesterday and filled up, drove around for a while, put the car in the garage and about 1/2 hour later noticed strong gasoline smell, looked at gas tank, fuel lines and filters, then noticed steady gasoline drip from charcoal canister. Took the gas cap off, and after about 10 minutes the steady drip stopped. My question is what would cause gasoline to flow to canister? Thought the valve on tank prevented gasoline from flowing to canister? Can the roll over valve/separator be bad? Checked it when had gas fume problem had no leaks or seeping. Help
Had the car out yesterday and filled up, drove around for a while, put the car in the garage and about 1/2 hour later noticed strong gasoline smell, looked at gas tank, fuel lines and filters, then noticed steady gasoline drip from charcoal canister.
Took the gas cap off, and after about 10 minutes the steady drip stopped. My question is what would cause gasoline to flow to canister? Thought the valve on tank prevented gasoline from flowing to canister? Can the roll over valve/separator be bad? Checked it when had gas fume problem had no leaks or seeping. Help
07-06-2015, 06:02 PM
#3
Instructor
Thread Starter
When you pulled the gas cap, IF you got any airflow/pressure outta the tank, that is your issue, you need a vented cap, my locking cap is vented, the one that came with the car was NOT, and so would keep that tank pressurized, the full tank seats the ball inside the black box up top and the rising fuel temps with driving in Florida sun will ensure that ball sticks there, fuel get warmer and warmer, especially with circulating back to the tank from engine/fuel pump....or like me if you have FI the circulation is even more....
Read another post and it seems that the line leading from valve on take to canister has a rubber valve inside of it that prevents gas from actually traveling to canister, that may be the issue as I think it was replaced with fuel hose. Going to get under cat this weekend and take the line loose to inspect. Thanks
07-07-2015, 01:09 AM
#4
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do I need canister vacuum lines?
I have a 77 and just put a new carb on it. It also has the vented locking gas cap. I eliminated the emission devices and the vacuum line to the charcoal canister. Do I need to have a vacuum line on it or not?
Also I am not positive where it is located but I think it is inside the drivers side fender?
Thanks
Also I am not positive where it is located but I think it is inside the drivers side fender?
Thanks
07-07-2015, 07:24 PM
#5
Burning Brakes
You don't use a vented gas cap if you are using the canister.
Gas leaking from the canister is a bizarre problem. If the tank is pressurized to where you need a vented cap, then you probably have a blocked return line from the canister.
I canot think of any other way gas might be sucked to the can.
Gas leaking from the canister is a bizarre problem. If the tank is pressurized to where you need a vented cap, then you probably have a blocked return line from the canister.
I canot think of any other way gas might be sucked to the can.
07-08-2015, 09:00 AM
#6
Team Owner
If you remove the vapor canister, you need to install a vented gas cap. The vapor canister IS the tank vent for cars equipped with it.
And, if you have a working vapor canister, you need to have a NON-vented gas cap. As far as why your car is dripping fuel from the vapor canister, I suspect that the fuel separator unit on the left side of the fuel tank is defective.
And, if you have a working vapor canister, you need to have a NON-vented gas cap. As far as why your car is dripping fuel from the vapor canister, I suspect that the fuel separator unit on the left side of the fuel tank is defective.
