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Road Runner vent lines

Richard Cranium

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I filled up the gas tank for the first time in The Pickle yesterday & when I parked it in my driveway (slight incline, nose down hill) I noticed a fuel pundde under the car. I put it on the lift & see two vent lines coming from the top left of the tank. One goes up through the trunk floor and down into the frane rail & the other basically is shaped like a candy cane & that's the one that was dripping fule. So, my questions are:

1. In the attached picture, is that vent line routed correctly?
2. Why are there 2 vent lines?
3. Can one be plugged?
4. If all is correct, what's to keep it happening every time the car is filled up?

Thanks in advance.
 

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That happened with my car. It still had the original tank in it and it was leaking where one of the two tubes went into the tank. I tried to seal it up but it didn't work so I put a new tank in the car. I don't know why there are two vent lines but one long tube goes up into the trunk area, and the other short one goes up towards the bottom of the trunk floor and exits there. I've had no more problems after changing the tank.
 
Thanks for the response, but the tank is not the issue in this case as the fuel was leaking out of the tube opening.
 
I just put a new tank in my car and it also had 2 vents and an extra connection in the gauge/pick-up insert. I got some 1/4 inch fuel line and 2 "T"s and ran all 3 in series to the line that ran up into the trunk and down into the frame rail. I have not filled the tank yet, but I put 15 gallons in tonight and took it on a 20 mile maiden voyage. (1 burnout and a 180 with no issues)
 
This set up is for that wacky fuel vent canister that prevents vapor lock. it sucks never worked well. Vent it to the filler neck and fogetabout it.
 
68 b bodies had 1 vent line from filler neck to atmosphere
69 and up had 2-4 vent lines, i cant find it here on google but the 68-69 manual has the location of the vent lines, i believe one went to the filler neck and the other looped up through the frame then back down but what your describing is that the vent line that is leaking is tooo short

double check the diagram though
 
If I recall, one of the two vent lines actually travels inside the tank to the opposite corner and the other has a short tube maybe a few inches from the edge. The two tubes I believe are to allow venting if the car is parked at an angle with a full tank, where one line can become submerged. And having a tube extension inside the tank will prevent exactly the problem you are having. A 70 tank has four vents with tubes running to all four corners. And like Benno says, a 68 tank has the single vent.

I recall my 68 RR having one vent line running up into the trunk, clipped to the RT wheel well, then back through the floor. The 69 had the small line making a loop like in your picture. The caps of course are non vented. I have to wonder if the tube that is leaking gas doesn't have the extension inside the tank (broken off some how).

As a side note I don't recall where the vapor separator line hooks to. I'm putting that system in my 69 and will have to find out sooner or later. I have a 70 tank in mine (because it was new and cheap at a swap meet) and I plan to tie my vents together to a manifold and maybe leave one for the vapor separator return.
 
Had this happen to me just yesterday on my 68 RR.
Filled up and drove to Wal-Mart parked and was on Level Ground and when i came back out i seen a puddle below the tank.
Checked both service manuals and they show nothing hooked up to the line that just loops around and down.
I am thinking Maybe the other vent line that goes up in the trunk might have got clogged!
I am just guessing also on it being clogged.
 
Both my Road Runners have the 2 vents like you have, and I have never had a problem. Could the longer tube be plugged? Does this car have the vapor separator with a return line running back?
 
I had the same thing happen on my 68 last weekend. I crawled under there to check it out but couldn't see anything. Let us know what you find.
 
Yes it is a system that never worked great but was the norm back in the day.
If you have a reproduction tank there is some talk of the tanks having the vents wrong and the fix was to swap the two vent lines between the two tank nipples.
If you search here or Moparts you'll see many threads on this subject.
Ron
 
Both my Road Runners have the 2 vents like you have, and I have never had a problem. Could the longer tube be plugged? Does this car have the vapor separator with a return line running back?

No vapor return line. For the benefit of others who aren't familiar with it; the vapor return line would return into the sending unit.
 
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I'll look at mine and see which one goes up inside the trunk and which one goes to the short tube. Maybe there is a difference between the 2 ports on the inside of the tank? Maybe one has a drop stem inside the tank and the other has a stem that stays high inside the tank?
 
This happened to me last year. I found one of rubber splice hoses was kinked. I took it off, shortened it up a bit, put it back on and have not had it happen again.
 
I just looked at my tank, the short hook shaped tube is to the far left and the one that goes up into the trunk is the right one.

Mine is hooked up the opposite of how yours it. Not sure if that matters, thinking it could be possible that on the inside of the tank one stem reaches down and one reaches high, not sure.
 
68 b bodies had 1 vent line from filler neck to atmosphere
69 and up had 2-4 vent lines, i cant find it here on google but the 68-69 manual has the location of the vent lines, i believe one went to the filler neck and the other looped up through the frame then back down but what your describing is that the vent line that is leaking is tooo short

double check the diagram though

Not true,68 GTX didnt have that one in the filler neck,just the 2 from the tank.One vent in the rail via the trunk and the other is sorta a S shape and vent under the car
 
Try to swap the two vents. One travels from the front to the rear, I think it should be hooked to the candy cane. The other only goes in a couple of inches, that one should be hooked to the one routed threw the trunk. Both travel near the top of the tank.
 
My 69 bee did the same last week when I filled it up with more fuel than normal.mine has the same set up with the candy cane shaped vent that doesn't hook to anything.it was a warm day and I was on a small incline.it quit dripping after a few minutes.
 
Try to swap the two vents. One travels from the front to the rear, I think it should be hooked to the candy cane. The other only goes in a couple of inches, that one should be hooked to the one routed threw the trunk. Both travel near the top of the tank.


I will try that!
 
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