Vapor Separator
Thread Starter
Instructor
Joined: Jul 2010
Posts: 103
Likes: 1
Vapor Separator
Guys, if the vapor separator is bad and fuel is going down the line does it trash the vapor canister? (hope not, I just replaced it!)
I've got a '73 that reeks of gas when the tank is very full and based on what I'm reading here I think it's one of 3 things:
1. I'm over filling the tank and the separator isn't doing it's job
2. There are hoses or gaskets at the top of the tank that have gone bad or...
3. Bad gas cap.
Although I can smell gas at the cap when I raise the fuel cap door, once the the gas tank gets down a ways the smell goes away. When the tank is topped off the smell is REALLY strong but by the time the fuel gauge drops to F it goes away.
I've got a '73 that reeks of gas when the tank is very full and based on what I'm reading here I think it's one of 3 things:
1. I'm over filling the tank and the separator isn't doing it's job
2. There are hoses or gaskets at the top of the tank that have gone bad or...
3. Bad gas cap.
Although I can smell gas at the cap when I raise the fuel cap door, once the the gas tank gets down a ways the smell goes away. When the tank is topped off the smell is REALLY strong but by the time the fuel gauge drops to F it goes away.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
I'm not positive, but I think the fuel vapor separator is only there to STOP fuel leaking out of the tank during a 'rollover' accident. It shouldn't have any affect on [liquid] fuel getting to the canister.
If that isn't correct, someone else can chime in.
Perhaps the vacuum operated switch on the vapor canister is not working properly. Or, maybe you've hooked up the vacuum lines incorrectly to that vapor canister.
If that isn't correct, someone else can chime in.
Perhaps the vacuum operated switch on the vapor canister is not working properly. Or, maybe you've hooked up the vacuum lines incorrectly to that vapor canister.
Melting Slicks
Joined: Mar 2005
Posts: 2,094
Likes: 298
From: Midlothian VA
Guys, if the vapor separator is bad and fuel is going down the line does it trash the vapor canister? (hope not, I just replaced it!)
I've got a '73 that reeks of gas when the tank is very full and based on what I'm reading here I think it's one of 3 things:
1. I'm over filling the tank and the separator isn't doing it's job
2. There are hoses or gaskets at the top of the tank that have gone bad or...
3. Bad gas cap.
Although I can smell gas at the cap when I raise the fuel cap door, once the the gas tank gets down a ways the smell goes away. When the tank is topped off the smell is REALLY strong but by the time the fuel gauge drops to F it goes away.
I've got a '73 that reeks of gas when the tank is very full and based on what I'm reading here I think it's one of 3 things:
1. I'm over filling the tank and the separator isn't doing it's job
2. There are hoses or gaskets at the top of the tank that have gone bad or...
3. Bad gas cap.
Although I can smell gas at the cap when I raise the fuel cap door, once the the gas tank gets down a ways the smell goes away. When the tank is topped off the smell is REALLY strong but by the time the fuel gauge drops to F it goes away.
The hoses are the first to go. With a full tank the brittle hoses will weep initially then leak as they break down over time. I was surprised at how brittle mine were when I replaced them.
The hose to the vapor separator will usually go bad before the separator. The separator is simply a big plastic check valve which allows vapors but not fuel to pass to the vapor canister. The check valve has a simple "ping pong ball" inside that floats when fuel rushes in and stops the liquid from going further. When the separator goes bad it's usually due to a cracked housing which lets fuel leak out when the tank if full. If raw fuel gets to your canister I doubt it would require replacing as it's function is to collect tank vapor for reburn by the carb. The vapor would frequently have the opportunity to condense into liquid while in the canister throughout the years depending upon weather/temp conditions which naturally occur.
I've never had a gasket nor cap leak.
So, I'd check your hoses. They're not really that hard to get to.
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
The hoses are the first to go. With a full tank the brittle hoses will weep initially then leak as they break down over time. I was surprised at how brittle mine were when I replaced them.
The hose to the vapor separator will usually go bad before the separator. The separator is simply a big plastic check valve which allows vapors but not fuel to pass to the vapor canister. The check valve has a simple "ping pong ball" inside that floats when fuel rushes in and stops the liquid from going further. When the separator goes bad it's usually due to a cracked housing which lets fuel leak out when the tank if full. If raw fuel gets to your canister I doubt it would require replacing as it's function is to collect tank vapor for reburn by the carb. The vapor would frequently have the opportunity to condense into liquid while in the canister throughout the years depending upon weather/temp conditions which naturally occur.
I've never had a gasket nor cap leak.
So, I'd check your hoses. They're not really that hard to get to.
The hose to the vapor separator will usually go bad before the separator. The separator is simply a big plastic check valve which allows vapors but not fuel to pass to the vapor canister. The check valve has a simple "ping pong ball" inside that floats when fuel rushes in and stops the liquid from going further. When the separator goes bad it's usually due to a cracked housing which lets fuel leak out when the tank if full. If raw fuel gets to your canister I doubt it would require replacing as it's function is to collect tank vapor for reburn by the carb. The vapor would frequently have the opportunity to condense into liquid while in the canister throughout the years depending upon weather/temp conditions which naturally occur.
I've never had a gasket nor cap leak.
So, I'd check your hoses. They're not really that hard to get to.
If there's a leak in that area, it drips right on top of the hot muffler. Beware. 
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,852
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
When a car is leaking fuel and it hits the exhaust, it will leave a brown colored stain on the pipe (or muffler).
Can you change the hoses without taking out the tank.. yes but it's not easy. While it's a pain to remove the tank it makes the job easier.
If you need the separator, we have them they run about 46.00 and if you use the sale coupon code you'll get it for 42.00. http://willcoxcorvette.com/advanced_...arator&x=0&y=0
Willcox
Can you change the hoses without taking out the tank.. yes but it's not easy. While it's a pain to remove the tank it makes the job easier.
If you need the separator, we have them they run about 46.00 and if you use the sale coupon code you'll get it for 42.00. http://willcoxcorvette.com/advanced_...arator&x=0&y=0
Willcox
Last edited by Willcox Corvette; Jan 10, 2012 at 10:28 PM.
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Safety Car
Joined: Sep 1999
Posts: 4,930
Likes: 11
From: AnyTown NJ
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Don't over look the fuel vapor separator. With a full tank on a hot day mine allowed raw fuel to travel
to the charcoal canister. The replacement was also defective (leaked fuel), the 2nd one worked.
Zip sells them.
http://www.zip-corvette.com/ProductD...GR-SR&CTitle=&
to the charcoal canister.
The replacement was also defective (leaked fuel), the 2nd one worked.Zip sells them.
http://www.zip-corvette.com/ProductD...GR-SR&CTitle=&
Burning Brakes
Joined: Aug 2004
Posts: 802
Likes: 1
When I parked my new 73 with a full tank on an incline, nose down, fuel would leak out of the canister. So I stopped filling the tank right up to the top.
I don't think these vapor seperator worked that great right from the start. As suggested above, it probably was there for roll-overs only.
I checked my original during my body off and there is no cracks anywhere and the ball still rattles.
Steve L.
73 coupe since new
I don't think these vapor seperator worked that great right from the start. As suggested above, it probably was there for roll-overs only.
I checked my original during my body off and there is no cracks anywhere and the ball still rattles.
Steve L.
73 coupe since new
Racer
Joined: Feb 2011
Posts: 384
Likes: 0
From: Northern New Jersey
I fill my 73 to 1 inch below the neck and have no odor problems. Did you check to see if you have a vented cap? If your canister had been removed for a time someone may have put i vented cap on it. Just something to look at. Also as suggested before the filler neck seal might be the problem since you don't see any leaks.
Thread Starter
Instructor
Joined: Jul 2010
Posts: 103
Likes: 1
Thanks, I've ordered a new cap since the old one is pretty crappy but think it's either the gaskets, hoses or the separator. Unfortunately the weather in Colorado went to hell so the snow's flying, the temps have dropped and the Vette is nose into the garage so this project is going to wait for better weather when I can take her out for a cruise to burn off the gas in the tank.
For what it's worth, I did find this article which seems to describe the process of dropping the tank.
http://corvettes.about.com/od/basicm...Easy-Steps.htm
About what I expected but I thought I'd pass it along.
For what it's worth, I did find this article which seems to describe the process of dropping the tank.
http://corvettes.about.com/od/basicm...Easy-Steps.htm
About what I expected but I thought I'd pass it along.
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
What are u running for the return line?
If u have a constant recirc from an EFI and electric fuel pump u can over-pressurize the tank and lines with a sealed cap. The vapor sep is to block flow at atmospheric press only.
Yes u can fill the Vapor Cannistor will a full tank of gas and a good right turn.
cardo0
Yes u can fill the Vapor Cannistor will a full tank of gas and a good right turn.
cardo0
