Revising my fuel tank vent line.

[timk225]

In bringing my 1973 Duster out of long term storage, One thing I had to do was replace the entire fuel system and rebuild the Holley 1 bbl carburetor. The only thing I didn't do was replace the vent line that runs along the fuel line, and I should have.

In fabricating a new vent line, I used a piece of rubber fuel line and a metal line to make a new vent. It comes out of the tank, runs across the front of the tank towards the drivers side, rising slightly, before a 90 degree down turn for a few inches.

I thought this would be good enough, but today I was transferring fuel into the car from gas cans at its storage place. After 8 gallons it was full, and fuel came pouring out the vent line until the fuel in the filler tube went down. It vents a little more than I planned.

I was wondering about installing some sort of catch can that would drain back to the tank once the need for venting was over. I suppose I could run a metal or rubber vent line up to the vapor canister in the engine bay, but didn't really want to do all that.

 

[Dana67Dart]

Have a look at 67 venting. Very simple and very effective. Basically it vents at the top of the filler tube then runs above that level in the trunk, then back down and out of the trunk into the left frame rail to atmosphere.

Keeps the ability to syphon at a minimum, and works very well.

 

[Oldmanmopar]

Put a vent at the top of the fill tube and run it down the tube through the rubber on the floor like 67-70 I installed a brass 1/8 nipple in the tube and ran a braided hose down. Use the vent on the top of the tank for a return. You'll need it with this new fuel. Get a return filter.

I drilled a small hole then spread the hole in the tube with and awl then a larger punch to give the 1/8 pipe tap material to thread.

 

[Professor Fate]

In bringing my 1973 Duster out of long term storage, One thing I had to do was replace the entire fuel system and rebuild the Holley 1 bbl carburetor. The only thing I didn't do was replace the vent line that runs along the fuel line, and I should have.

In fabricating a new vent line, I used a piece of rubber fuel line and a metal line to make a new vent. It comes out of the tank, runs across the front of the tank towards the drivers side, rising slightly, before a 90 degree down turn for a few inches.

I thought this would be good enough, but today I was transferring fuel into the car from gas cans at its storage place. After 8 gallons it was full, and fuel came pouring out the vent line until the fuel in the filler tube went down. It vents a little more than I planned.

I was wondering about installing some sort of catch can that would drain back to the tank once the need for venting was over. I suppose I could run a metal or rubber vent line up to the vapor canister in the engine bay, but didn't really want to do all that.

If you're talking about the fitting at the top of the tank, above the fuel sender, that is NOT a vent line in the purest sense of the term. It is a fuel/vapor return line, and in order for it to do any kind of venting it needs to be routed through the charcoal cannister EXACTLY as the factory had it routed. The way you have it hooked up, it is not going to do anything but piss fuel all over the ground until the fuel level drops below the fitting. No different than if you punched a nail in the tank- it'll just leak until the level drops below the hole. A "catch can" won't do a thing- if it's sealed, it won't vent; and if it's not sealed it'll just overflow.
Bite the bullet and run another line up to the charcoal cannister like you know you should have done in the first place. What was wrong with the original line?
If a line to the cannister is no longer an option, then do as Dana and OMM said- put a fitting at the top of the fill tube and loop a hose up towards the C pillar then down along the filler tube and out the trunk floor.
Better yet, after seeing your other thread about installing a Super 6 setup, wait until you have it and then copy EXACTLY how the fuel and vapor system was connected and plumbed on the donor vehicle.

 

[timk225]

If you're talking about the fitting at the top of the tank, above the fuel sender, that is NOT a vent line in the purest sense of the term. It is a fuel/vapor return line, and in order for it to do any kind of venting it needs to be routed through the charcoal cannister EXACTLY as the factory had it routed. The way you have it hooked up, it is not going to do anything but piss fuel all over the ground until the fuel level drops below the fitting. No different than if you punched a nail in the tank- it'll just leak until the level drops below the hole. A "catch can" won't do a thing- if it's sealed, it won't vent; and if it's not sealed it'll just overflow.
Bite the bullet and run another line up to the charcoal cannister like you know you should have done in the first place. What was wrong with the original line?
If a line to the cannister is no longer an option, then do as Dana and OMM said- put a fitting at the top of the fill tube and loop a hose up towards the C pillar then down along the filler tube and out the trunk floor.
Better yet, after seeing your other thread about installing a Super 6 setup, wait until you have it and then copy EXACTLY how the fuel and vapor system was connected and plumbed on the donor vehicle.

Yes, you're right, I should have just gotten the vent line from year one as well as the fuel line. The original line was all clogged up from 20 years of sitting. I tried for a week to flush it out with vinegar and water at different times, and blowing air through it at 60 psi from an air compressor. 60 psi would get through but normal free flowing unpressurized air would not. Despite getting a lot of brown gunk out it was still too clogged.

I have some suspension components on the way (lower ball joints, lower control arm bushings, strut rod bushings, idler arm) as well as a new power steering pump and driveshaft U-joints, a local mechanic who knows these cars will put it all in. I'll tell him to run me a new 1/4" vent line up to the cannister as well. Cheapest and easiest way to do it.

 

[67Dart273]

If you're talking about the fitting at the top of the tank, above the fuel sender, that is NOT a vent line in the purest sense of the term. It is a fuel/vapor return line, and in order for it to do any kind of venting it needs to be routed through the charcoal cannister EXACTLY as the factory had it routed. The way you have it hooked up, it is not going to do anything but piss fuel all over the ground until the fuel level drops below the fitting. No different than if you punched a nail in the tank- it'll just leak until the level drops below the hole. A "catch can" won't do a thing- if it's sealed, it won't vent; and if it's not sealed it'll just overflow.
Bite the bullet and run another line up to the charcoal cannister like you know you should have done in the first place. What was wrong with the original line?
If a line to the cannister is no longer an option, then do as Dana and OMM said- put a fitting at the top of the fill tube and loop a hose up towards the C pillar then down along the filler tube and out the trunk floor.
Better yet, after seeing your other thread about installing a Super 6 setup, wait until you have it and then copy EXACTLY how the fuel and vapor system was connected and plumbed on the donor vehicle.

Actually it IS the vent line as part of what you describe. There is NOTHING else in those fuel systems that does the function of "venting."

I concur with everyone else, if you cannot or don't wich to re-create the original carbon can system, either run the line back up front and get it "high" in the bay, and then either terminate in a breather or T it into the PVC vent system, or else convert the filler to the old 69/ earlier system.

 

[timk225]

I'm taking the car in to get the other parts put on (I know how to do it all but don't have the time, tools, of a good place to work on it) and I'll have the mechanic run a 1/4" metal line up to the charcoal canister. Copper, steel, whatever he has laying around.

Regarding the charcoal canister, I seem to remember them being just a can with a mesh filter at the bottom. Is that right or are there supposed to be more parts inside?