OK, this girgling sound is driving me nuts, the car is a 71 roadrunner 440 six pack, all stock. When I come back from a drive, shut the engine off, get out of the car I hear this girgling noise coming from what it appears the fuel separator that is located in the left rear whellwell. I don't know if its sucking fuel from the gas tank or the carb of something else. The car is hard to start when it sits for more than a week, but I hear this often. From my understanding there isn't supposed to be any fuel in this seperator right? Its only supposed to be vapors. Anybody ever hear of this?
Now I posted two pics , one the seperator itself with the five lines and one of the plumbing when I put the car back together.
Also i have a link to a you tube video with the noise its making. I took this by putting my phone inside the whell well and recorded a short video. This is my firstime to to this link so bear with me if it doesn't work the first time.
Link to noise https://youtu.be/uPeCVUxw08I

Maybe I got the plumbing wrong, I am also wondering if this is why it always seems that my fuel bowl at the carb is low on fuel

Any help would be appreciated.

Your fuel has a lower boiling point due to the alcohol content in it which makes it way easier for vapor lock and fuel boiling over in the carb. I had this on my 65. Whenever I got back from even a 20 minute drive, I could hear fuel boiling in the tank. My 3" TTI exhaust pipes were 1-2" away which did contribute to the issue but the fuel also burned hotter causing more engine heat. Fun stuff. Did you take the filler cap off and get a whoosh of air? May need to look into a way to make the venting better so the tank pressure can drop.

Interesting, i didn't think that would be possible, i guess the two tailpipes run on each side of the tank. Next time i will take the fuel cap off and see if air comes out. If this is happening it sounds dangerous.
If anyone has any other suggestions I'm all ears

I have seen this on a couple of cars in the past. I think it is a venting issue. Check that your lines are right. You could try driving with the cap loose and see if it is gone before looking further. Could be something as simple as the cap. I used to have an Olds 442 that did this, swapped cap and it went away. Long term answer on the Olds, turned out the lines weren’t hooked up correctly for the tank venting.

What kind of cap do you have? Is it vented or not?

This is the gas cap I'm using, pressure vacumn, which is not vented i believe as that seperator is supposed to capture and direct the fumes to the crankcase. I'm I understanding it right. Question could I use a vented cap in such a system?

I'm going to check the hose routings to make sure its plumbed correctly but I believe its done correctly based on the pics I took when assembling

I could be wrong, but I thought that cap should be vented. A quick search of Rock Auto, what they are selling for 71 Road Runners are vented caps, several to choose from. Try that.

I think what happens is you are right about where the fumes go, but there still has to be some relief in the system to let air in to the tank as the fuel and fumes are vacuumed out. Read the description for the Stant 10807 cap, it sort of explains it.

Was there a difference between CA. emissions and the other 49 in 71?

Joe

I would think that a gurgling sound in a tank would indicate air or maybe liquid being pumped in, or disturbing the existing fuel somehow.
That system has a BUNCH of hoses & stuff going on. I'd want to consult the FSM on all that.
After 45-50 years, I wonder if it's all still working correctly.
If the carb bowl is open to atmosphere, it can lose fuel through evaporation.
If the carb bowl is sealed, as in part of that system, I'd wonder if heat expansion is returning fuel to the separator and/or tank.

Probably so I have check a bunch of early Mopar gas caps, some are vented and some are not but do have a vacuum check valve in them that will open up under vacuum, you can check them by sucking on the bottom of them
The CA clean air packages varied from year to year

I also found this write up in the service manual. It appears I have the right one. Can you somehow check to see if the cap works???

Since the fuel has a lower boiling point, it really taxes the venting that the cars came with. When I get back to work on my 65, I'm going to look into putting a vapor canister onto it, like what came on the 73 and later stuff, to see if I can control some of that vapor especially when its sitting in the garage or other closed space.

Interesting about the cap, didn’t know that one, learn something everyday!

Depends what you are trying to do...I would still suggest doing something that would confirm or rule out lack of venting by seeing if you can make it go away...different cap (narrowed down by one that fits the filler neck, so not a lot of choices). From there, if confirmed, your cap is bad as you mentioned or the plumbing.

Im going to try and test the cap today as someone mentioned. I also tought about fuel being returned to the tank but I think it all connects up the the 3 nipple valve cover breather, so there is no direct line back to the tank from say the fuel bowl vent.

I tested the gas cap with compressor and the valve did open under pressure. So I'm assuming this part is ok.

Next question, how would you clean the air breather on the valve cover, I'm looking for possible blockage, and if this thing is all mucked up inside maybe the system is not functioning properly