Fuel Vent - What to do?

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Joined
Aug 8, 2018
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Location
California
My Car
72 Fastback - 351C-4V, Fitech EFI, T56 Magnum 6 Speed
My car doesn't have the original canister let alone anything else emissions related and not much stock. Beyond that the vent line on top of the tank leaks so when I fill the car up, the gas will spill out of the top of the tank. The solution so far has been to avoid filling the car up all the way. Oddly enough there's rarely any fuel smell around the car even with that vent open. Well now after getting stuck on the side of the road again from plugged up fuel filters (EFI), I think it might be time to replace the tank so I don't have to deal with the dirty gas anymore and can take care of that vent issue.

If I go down that road, I'd like to at least be able to fill up the tank. So what do I do with that vent line? This car isn't stock so I'd just assume not add a canister to the engine compartment. I would however be fine adding one somewhere under the car (higher than the tank I assume?) if there's a good place for that. Or can I get away with plugging the vent if I vent the cap or something like that?

Thanks
 
Do you have an in-tank pump and return line. I ask because some time ago, Kilgon created an interesting in-tank pump tutorial, using the vent opening that I’m currently using on my late 80’s stock Ford EFI system. Here is the tutorial:

https://7173mustangs.com/threads/in-tank-fuel-pump.40147/
You could always do what the factory did before charcoal canisters, and run the vent hose up the panel.
 
I have an external pump and return plumbed to a bung welded to the pickup plate. If I do end up replacing the tank, I could put a new pickup in there and plumb the return to the vent line. Both seem tidy, but the return to the vent seems like a good way to deal with that.

What do you mean by vent hose up the panel? Like up a body panel or something?
 
I went with the aeromotive stealth in tank setup. I am very happy with it.

look on Amazon for a charcoal inline filter. Google might help, too. Street orders use them. I used to have a link but I cant Find it now.
 
I have an external pump and return plumbed to a bung welded to the pickup plate. If I do end up replacing the tank, I could put a new pickup in there and plumb the return to the vent line. Both seem tidy, but the return to the vent seems like a good way to deal with that.

What do you mean by vent hose up the panel? Like up a body panel or something?
On my 70 Torinos I have had they just vent the tank to a panel behind the rear bumper.
71 and up they added the canisters and I assume 71 emissions stepped up a little over 70.
 
The 71-73 fuel evaporative systems turned out to be very well designed. They did the job of dramatically reducing fuel vapors evaporating from a fuel tank, and did not have any kind of detrimental impact on how the engine runs. Personally, I would suggest trying to purchase the various parts, new or used, and put together a replacement system as close to the manufacturer as possible. I have attached a few files that contain more info on the fuel evaporative system used for 71-73 Mustangs.

https://www.youtube.com/watch?v=n9woMnHByts
 

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Thanks. Excellent info as usual.

I didn't really think the vent or canister would have any negative effect on anything other than just taking up space under the hood. I'm also not running a stock air cleaner so I'd have to cobble something together to make that end of it work. I'll take a look into it or maybe seeing about mounting something up under the car closer to the tank that way I can say it has an emissions system :) .

I assume a direct vent tube or canister needs to be mounted higher than the top of the tank, correct?

Looks like a simple solution would be to use a breather valve like one of these https://www.summitracing.com/search/part-type/fuel-tank-cap-vents that let's it breath but won't spill gas. Won't do anything about gas smell from the vent but does at least solve the what to do issue for pretty cheap.
 
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Yea, I had a 1969 Torino, and the vent hose was routed up the passenger sail panel, and the end had a valve which looks like the one you posted. It still had more gas odor than my 71 Mustang, which had the charcoal canister.
 
My solution was using the gas filler cap for venting. I guess this depends on which cap you have. Mine had a diaphragm on it that I think only allowed air in but not out. Said diaphragm was broken on mine so it now allows air in and out. I have been running it like that for a few years.

Edit: as I read your first post I do have gas spill through the gas cap if too full and left parked. If I fill it up and drive it is fine but if I fill it up to the top and then park it in my garage fuel will come out. This is more pronounced when my garage is hotter than outside. What happens is that the fuel expands with the heat and makes its way up the filler tube.
 
Thanks. I live a couple miles from the gas station so figure that'll use up a gallon or two of gas and I'll never have a full tank when parked, so shouldn't be a problem for me. :D
 
If the large rubber/plastic fill tube seal is installed backwards it will leak fuel. Chuck
 
The 71-73 fuel evaporative systems turned out to be very well designed. They did the job of dramatically reducing fuel vapors evaporating from a fuel tank, and did not have any kind of detrimental impact on how the engine runs. Personally, I would suggest trying to purchase the various parts, new or used, and put together a replacement system as close to the manufacturer as possible. I have attached a few files that contain more info on the fuel evaporative system used for 71-73 Mustangs.

https://www.youtube.com/watch?v=n9woMnHByts
In my opinion I would suggest installing the vapor return line like it was manufactured not for originality but as a matter of good practice. I replaced ALL lines and parking brake cables with SS so they would look good forever and not to make a show car. I do this as a matter of practice on all of the cars that I have restored. Thx, Bill
 
We'd all like to get hold of a charcoal canister but they are as scarce as hen's teeth.
Looked at some. modern ones but they are all encumbered with computer controlled valves.
Going to have to mungrilize a modern one or start with an old paint can.
That's funny.....My dictionary doesn't recognize mungrilize????
 
Yeah, I suppose lots of people simply discarded the "smog" equipment from their cars back in the day. I'm lucky in that both of my '72s (Mach 1 and convertible) both have the original charcoal cannisters still in place. I bought the Mach 1 in 1977 and the convertible in 1980, so they were basically untouched when I found them. I won't make you guys jealous by telling you what I paid for them. Let's just say that their value has multiplied many times over since then. I hadn't realized the charcoal canisters had become so hard to find!
 
My charcoal canisters are stay right where they are! My convertible is a Q code C6 car with just about every option in the book, even power windows, intermittent wipers, and power seat back releases and the 3 spoke tilt steering wheel.20170424_153315.jpg
 
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