...Is the only source for a leak in that area from the tank itself?

After doing a good bit of research here tonight it seems that only the 75 and 76s had extra fuel lines, filters, and pumps up front under the tank, and that my '74 should only have the two lines under the tank, which are new, on the passenger side of the car. I also believe that the hard lines run through the tunnel and don't come near the driver side of the car..... Perhaps leaving only the tank as the possible culprit?

I'd bet you probably need to change the hose / filter under the tank too. Pull the inspection panel in the front trunk. Disconnect the battery just to assure you have no source of ignition and work backwords, you probably would be looking at replacing the plastic fuel lines in the tunnel. Stainless is a good option.
The gas will disolve the tar and create a mess if it sits too long, as well as being dangerous.

I probably don't need to say this, but don't drive it until you figure this out. I would not park it in your garage either.

Too many of these cars have burned up.

If you still have the old plastic fuel lines in the tunnel they could be cracked.

I was not sure from your message if you replaced those.

Otherwise, it sounds like the rubber hoses under your tank may be cracked or not sealing well.

There are different diameter lines needed (which is a stupid design to me) and if you try to clamp the larger one where the smaller one belongs they will leak. Seems like they are 10mm and 8mm. 10mm to the larger nipple in the tank and then 8mm to the fuel filter (?). Some vendor sells a hose that is 10mm on one end and 8 mm on the other. I am not making this up.

John

The lines under the tank and the center tunnel lines are more likely culprits than the tank itself for fuel on the floorboard.

--DD

From the searching on the forum I did tonight I was under the impression that '74s do not have the filter under the tank, is that not correct?

I also did a quick looksee for the inspection panel that I found referenced in some other threads. I didn't see and assumed that my '74 didn't have one. Is there one, and if so where would it be located?

The tunnel seems dry btw. The fuel seems to be emanating from in front of pedal assembly leaking through the front firewall separating the hell hole from the cabin.

This may sound stupid but could it be brake fluid and not gasoline?

The brake master cylinder could be leaking right at the front wall next to the pedals.

If you are sure it is gasoline, I would drain and remove the tank to see what is up.

John

bad master cylinder

Agreed. If it's brake gas you can smell it, if it's an oily substance, bad master cylinder. Either way tyhe fuel lines (if they are original) will eventualy need to be replaced. Chris has them.

Happened to me over the summer.

A while back I had a rust spot on the gas tank that developed into a leak, but it dripped out from under the car instead of into the cabin. If it is fuel, check the spots where the tank is against other surfaces for rusting which can cause a leak.

No doubt it's fuel....unless if the previous owner managed to find a way to run the brake hydraulics off of some sweet swelling 93 octane.

There are two short pieces of metal tubing that go from the rubber hoses under the tank, thru the rubber grommet, and connect to the plastic hoses thru the tunnel. I'm betting the leak is at the plastic line to metal tubing in the tunnel. Pull the carpet from the tunnel by the pedal to expose a small inspection plate. With a mirror and flashlight, you can see in the tunnel. Sounds like its time for all new lines and hoses.

pull the tank out and replace the rubber hoses that go from the tank to the plastic fuel lines in the tunnel.
I bet you will find those are cracked and leaking, and the gas is running down the outside of the fuel line into the tunnel...

The lowest spot on the floor is underneath the pedal cluster.

rich

That is correct. The 74 cars originally had the pump and the filter located under the engine shelf, like the 70-73 cars. A relatively popular modification is to move the pump up to where the steering rack lives, but it probably has not been done on the majority of 70-74 cars.

If it's fuel, only two real possibilities:
- The fuel lines in the center tunnel are leaking
- The fuel tank has rusted (or abraded, but much less likely!) to the point where there is a hole, and the gas is finding its way into the cabin instead of under the car. Possibly through another rust or abrasion hole.

....Or, if someone installed aftermarket equipment like a stereo, air conditioning, alarm, or some such, the installer could have run a screw into the tank... Similar things have been known to happen.

--DD

Welp...had a couple minutes today and pulled the tank and it was indeed the culprit. The leak is the 2" wide wet spot in the center of the photo. Rusted straight through. Looks like the fuel was leaking down the little shelf that that part of the tank sits on, and made its way into the cabin through the steering rack cavity.

Not sure if this is good news or bad news. The good news is I don't have to worry about going through the pain in the arse of changing/feeding lines through the tunnel. The bad news is that one of the radiator shops in town that I was going to take it to to boil and patch is closed from Dec 13th -Jan 7th, apparently they can go a month every year sans any income, and the other spot in town mystifialbly just closed down.

Change the tunnel lines while you have the tank out. They are plastic and 40 years old. My lines inside the engine compartment literally crumbled in my hands when I pulled them this summer.

Rust and gas fires are the enemies of the teener. And doofuses running into you from behind.

Olin

Get some fuel lines from Tangerine Racing. Replacing the isn't really that big of a job. Even if it is a pain in the ass, it affords great piece of mind. I used truck brake lines but that was before I new pre-bent ss lines were available. CHANGE THE FUEL LINES.

+1 on what Elliot says! I will be changing my lines this winter also.

"Change the tunnel lines while you have the tank out. They are plastic and 40 years old. My lines inside the engine compartment literally crumbled in my hands when I pulled them this summer. "

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Take the time and do the complete job. . . pulling the tank it the hardest part. . you're more than 1/2 way there. . It's all about being safe. . . . and keeping us from saying "I told you so" if the car burns up later

Change the fuel lines!

Oh, the drama!

This is better than chopper build off.

I may have a spare tank you can have. Let me make sure it is good.

John

Same thing happened to my tank 25 years ago. Water got to that felt pad and the tank developed a pin hole leak but only when I filled it up. Leaked down to the pedals.

Also if you have orginal soft plastic pedal bushings and your MC leaks it will eat up those bushings.

BTY, when I pulled and replaced my plastic tunnel lines. I put them in my vice and tried to get them to crack. They wouldn't. They compressed completly yet didn't crack.

That's not the first time that a tank has rusted out where it sits on the felt pad. The pad holds water like a spunge.