fuel tank lines?

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mopower440

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On my 1972 dart swinger, there are 2 metal lines that come from the gas tank and stop under the hood. On one of them, i have a rubber hose running to the fuel pump and the other one is just open. I ve been running it like this forever but dont like the fact its just open. What is it supposed to go to? Im assuming it originally went to a charcoal canister or something? if so, i dont have that canister now, what should i do with it? Im sure it has to be open to vent the tank but is there something that can keep stuff from getting in it?
 
Im pretty sure it originally went to a charcoal canister. I did not put that back in so what can i do with the line now? Im afraid i cant just cap it off because it wouldnt let the tank vent but not sure on this?? anyone?
 
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Sounds like a Vapor return line if used with the correct fuel filter and or possibly a vent line for a charcoal canister back to the tank.

Go to mympopar.com and download a service manual for more information!
 
Yup i just completely redid the fuel lines on my 70 Dart...the one line that comes up on the left side of engine compartment on the passenger side, right after the firewall is a return line that goes back to a canister that's generally standing up in the driver's side trunk. In back of The driver side left rear wheel has a little compartment with three screws that hold up a cover that allows you to see the four lines that vent to tank.. I capped off three of the lines and only use one back to the canister to vent it

20170430_135901.jpg
 
The one top Short Line is where the return line returns to that canister ...the four lines there are the lines that run to the tank that vented from all four corners
 
You can very easily use it for a liquid fuel return.
 
I added a charcoal canister to my '72 Demon. If you want you could use a short hose and install a small engine fuel filter . That would let it breathe and still keep foreign material out. Before I replaced my missing charcoal canister I always had gas fumes in my shop.
Yote
 
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440DART1970 said:
Yup i just completely redid the fuel lines on my 70 Dart...the one line that comes up on the left side of engine compartment on the passenger side, right after the firewall is a return line that goes back to a canister that's generally standing up in the driver's side trunk. In back of The driver side left rear wheel has a little compartment with three screws that hold up a cover that allows you to see the four lines that vent to tank.. I capped off three of the lines and only use one back to the canister to vent it

View attachment 1715046400
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Holy crap did they change that much from 69 to 70? Was this from a Cali car?
 
Yote said:
I added a charcoal canister to my '72 Demon. If you want you could use a short hose and install a small engine fuel filter . That would let it breathe and still keep foreign material out. Before I replaced my missing charcoal canister I always had gas fumes in my shop.
Yote
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Is it a danger being it is venting tank fumes under the hood? its always worried me..I like the dea of a small filter on the end of it as long as it doesnt create a hazard from the fumes under the hood..
 
mopower440 said:
Is it a danger being it is venting tank fumes under the hood? its always worried me..I like the dea of a small filter on the end of it as long as it doesnt create a hazard from the fumes under the hood..
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I would say so, yes. If you can smell fumes, they can ignite.
 
Don't use it for a return or plug it unless you make other arrangements for a vent. That 1/4 line --which went to the canister--IS THE vent

As said above.......you can go to MyMopar and download service manuals. These systems changed over the years.

1....Nothing before 70 had them, and only some 70's, CA state notably

2...I think but not sure that 71/ later all cars had it

3...First few years they used a big long tank up in the trunk, "vapor separator."

4...Later years incorporated this function into the tank itself, so no separator in the trunk

5....Pay extra attention to fuel caps. They changed in the years with these systems. "Somewhere on here" is a thread on the different caps
 
Exactly! I left out about the vent because......well.......some things just go without bein said. If you use the vent for a return, you need a vented gas cap for sure.


67Dart273 said:
Don't use it for a return or plug it unless you make other arrangements for a vent. That 1/4 line --which went to the canister--IS THE vent

As said above.......you can go to MyMopar and download service manuals. These systems changed over the years.

1....Nothing before 70 had them, and only some 70's, CA state notably

2...I think but not sure that 71/ later all cars had it

3...First few years they used a big long tank up in the trunk, "vapor separator."

4...Later years incorporated this function into the tank itself, so no separator in the trunk

5....Pay extra attention to fuel caps. They changed in the years with these systems. "Somewhere on here" is a thread on the different caps
Click to expand...
 
67Dart273 said:
Don't use it for a return or plug it unless you make other arrangements for a vent. That 1/4 line --which went to the canister--IS THE vent

As said above.......you can go to MyMopar and download service manuals. These systems changed over the years.

1....Nothing before 70 had them, and only some 70's, CA state notably

2...I think but not sure that 71/ later all cars had it

3...First few years they used a big long tank up in the trunk, "vapor separator."

4...Later years incorporated this function into the tank itself, so no separator in the trunk

5....Pay extra attention to fuel caps. They changed in the years with these systems. "Somewhere on here" is a thread on the different caps
Click to expand...

Exactly this. Here's some more in depth info. Courtsey of @slantsixdan

For '72, things got very much better. At the back of the car, the inner tank was deleted; by clever shaping of the top dome area of the tank, the same function was achieved by means of a controlled air pocket at the top of the inside of the tank. The '72+ tanks also have only one vent fitting. At the front of the car, the crankcase was no longer used to contain fuel vapors. Instead, a canister containing activated charcoal granules was mounted at the front corner of the engine bay. Lines lead to it from the carb bowl and the fuel tank vent. There is a purge valve mounted atop the canister, with a small diameter vacuum line teed into the distributor vacuum advance line, and a large diameter line from the underside of the purge valve, teed into the PCV valve hose. There's vacuum in the distributor vacuum line only above idle, so the purge valve only opened above idle. Voila, no more hot start/hot idle problems, since fuel vapors were only drawn off and burned above idle. This system works fine.
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As for the gas cap. The stock gas cap is not vented. It is a pressure/vacuum fill cap. Here's the excerpt out of the manual:
filler2-jpg.jpg

filler-jpg.jpg


And some more info courtsey of @slantsixdan

A-bodies do not use vented caps. The car needs what is called a "pressure-vacuum" fuel cap. It is vented, in a manner of speaking, but it's not the same as what is commonly referred to as a "vented" fuel cap. A vented cap has a passageway for air to flow in and fuel vapours to flow out. A pressure-vacuum cap also does, but has two spring-loaded check valves -- one very low-tension one controlling inward flow, and one high-tension one controlling outward flow. Pressure-vacuum caps were first used in '70 on cars sold in California, then in '71 throughout the US and Canada. The design of the cap was changed in the middle of 1971 production. The cap for your friend's '72 Scamp is a late-'71 through '76 item. The '70-'71 cap will not fit correctly. A pre-1971 (pre-1970 California) cap is unvented and will not fit or work correctly.
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On my car, 72 scamp, that line is just cut off shortly after the metal pipe in the engine bay. It's never cause me any problems. But it's on my list of things to fix. I am probably going to either use it as a return line when I do my EFI and vent the tank differently. Or leave it as a vent with a filter of some kind. I'm not sure which way I am going to go yet. But am leaning towards turning it into a return and venting the tank differently.
 
Lustle said:
Exactly this. Here's some more in depth info. Courtsey of @slantsixdan



As for the gas cap. The stock gas cap is not vented. It is a pressure/vacuum fill cap. Here's the excerpt out of the manual:
View attachment 1715046427
View attachment 1715046428

And some more info courtsey of @slantsixdan



On my car, 72 scamp, that line is just cut off shortly after the metal pipe in the engine bay. It's never cause me any problems. But it's on my list of things to fix. I am probably going to either use it as a return line when I do my EFI and vent the tank differently. Or leave it as a vent with a filter of some kind. I'm not sure which way I am going to go yet. But am leaning towards turning it into a return and venting the tank differently.
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I don't need a return line, never had one, so I guess I need to find some sort of filter to put on it..not sure where to find something like that..
 
slantsixdan said:
Read this.
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I read it and is interesting, but this is a hot rod and i would prefer not to put a charcoal canister under the hood to run this line to and i dont run the vacuum advance.. any other ideas on what to do with this open line?
 
mopower440 said:
I read it and is interesting, but this is a hot rod and i would prefer not to put a charcoal canister under the hood to run this line to and i dont run the vacuum advance.. any other ideas on what to do with this open line?
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Why? The charcoal canister can help BOTH performance AND fuel economy. It's a win/win.
 
mopower440 said:
How so? and because i dont have one and dont know of any in the bone yards..
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Use your head and think about it.

It's a charcoal canister. It removes spent fuel vapors, returns them to the tank where they condense back into liquid gasoline. It helps keep cool fresh fuel at the carburetor. It's not that hard to figure out.

Just because something is emissions equipment, doesn't make it all bad.
 
BB A body cars with a return line, even if using just the separator type fuel filter make sense. All the other spaghetti shown earlier is overkill (IMO) unless the jurisdiction requires it!
 
RustyRatRod said:
Use your head and think about it.

It's a charcoal canister. It removes spent fuel vapors, returns them to the tank where they condense back into liquid gasoline. It helps keep cool fresh fuel at the carburetor. It's not that hard to figure out.

Just because something is emissions equipment, doesn't make it all bad.
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I see..Dont know where to find one. Just did a search at my local pullapart for all a-body mopars..none..
 
1969383S said:
BB A body cars with a return line, even if using just the separator type fuel filter make sense. All the other spaghetti shown earlier is overkill (IMO) unless the jurisdiction requires it!
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You said balls.
 
mopower440 said:
I see..Dont know where to find one. Just did a search at my local pullapart for all a-body mopars..none..
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There wont be any. Because stupid people throw them away. They can be very beneficial to mild to moderate street cars. You simply cannot tell people that. They won't listen.
 
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