Got back to my garage after a short drive in my 73 Challenger, once I had opened the garage door and walked back to the car there a fairly large puddle of fuel on the floor leaking onto the diff, quickly looked underneath the car but could not see where it was coming from, so started the car again and looked underneath but no leak, I did notice this pipe(see below pics) just above the diff in front of the tank but could not confirm if this was where the leak was coming from, is it some kind of fuel overflow pipe ?

I did fill the car up yesterday to almost 3/4 of a tank so is it possible the gauge is inaccurate and I have just really overfilled it ?

I haven't owned the car long so i'm not too familiar with the accuracy of the gauge yet

I put the car back in the garage and checked again for any leaks but again there was nothing ?

Thanks for any help

Any idea on this? It's definitely leaking out of that pipe after driving for a bit

That is the vapor separator. That fitting there would normally connect to the vapor line which runs to the charcoal canister in the engine bay. I am assuming all that is gone as most people tear that out over the years.

Mine will do the exact same thing if I really fill the tank up and let it sit on a hot day where I will find a little puddle of fuel under my diff and have my wife fuss at me about a smelly garage.

You could either reconnect that to the vapor line if you still have it or maybe take a 1/4" rubber fuel/emissions line and run it into the frame of your car somewhere which might help.

Other wise, I'd say just don't top off your tank all the way and give it some breathing room.

No don't think so ?

I drove the car yesterday to use some fuel and kept checking and no more leaking as more fuel was used, so I assume the gauge must be way off

It was leaking when the gauge was reading just over half a tank so I guess when the gauge reads empty there is probably at least a quarter of a tank still in there ?

Those 4 lines go into the Vapor separator it stopped being in the trunk after 71.

Like was said that copper line was supposed to go the Charcoal canister in the engine compartment.

I would run a new line to a charcoal canister or like he said do not park it with a full tank.

Your fuel tank vent system has been "jury rigged" and is no good. It'll always smell in the garage and always leak no matter how full the tank if you ever park on a incline.

There's no reason not to use the factory vent system. You don't have to use the charcoal canister if you don't want. The vent line goes up to the engine compartment and it can be left open, connected to the air cleaner, connected to the valve cover breather or connected to the charcoal canister.

That's also very dangerous and you are gonna have a fire soon like that, hope no one sends a cig under your car.

That tubing if it's copper is not even there on a stock setup. Like said it should connect to the vent line.

Here's what it should look like.

What this thing does is provide one place for all four vent lines to terminate and then one line goes to the front up high, higher than the gas tank to provide tank venting. It can't leak out up front because it's higher. And even if you leave it unconnected up front it does not put out gas smell because it's so far from the tank.

Then there are four vent lines inside the tank and one of them are always open to the air inside your tank no matter how the car is sitting providing a vent. Each one goes to the upper 4 corners of the tank. Pretty simple really but very few people understand how it works. Hope this helps.
Here's the four vent lines inside the tank, they should never be plugged off.


I recondition/restore with the old hoses in place to protect the nipples and to keep the clean up material out of the separator.

Those four steel lines in the tank allow you to fill the corners up all the way by letting the air inside the corners escape My 1971 Duster had the same set up If you listen real carefully when filling the tank up you can here the air escape through those lines, mine had one hose from that device into the tank vent, at least that is the way it ended up being plumb by me I would fill it up all the way into the filler tube so I could see it was full Them dang stroker motors need a full tank to be able to go out and play with all the time