Still struggling with gas odor in front trunk around expansion tank
Installed a new gasket between the fuel tank and expansion tank, and there is a metal ring on top—Just trying to verify the gasket placement is there supposed to be another gasket under the metal ring or is mine in the wrong placement.

The fuel odor seems to be coming from that area so I also ordered a new gas cap seal and I have already replaced the 4-5mm hoses to the expansion tank . And already replaced gasket under fuel sensing unit all the bolts are tight

Today I was going to see if it’s possible to lift the tank and check all the hose connections. All the hoses are new with new clamps. The inlet tubes are not leaking

Edit: checked under tank it’s bone dry and zero smell whatsoever so now consider that unless I’ve done something wrong on the expansion tank install that the odor must be the fuel cap gasket even though it’s super tight and nothing visible wrong. Have ordered one

there is supposed to a large circular rubber gasket beneath those 8mm screws. Its like 2 mm thick, you could probably make one out of cork or sheet gasket material

yes maybe the lines on the bottom of the tank are weeping, pull the tank up and look

Maybe your gas tank has a hole in it. I found that my tank had a hole in it due to rust eating it away from the felt pads glued to the tank where it rests against the body. Several used tanks I looked at also had the same problem. The leak isn’t bad enough to leave a puddle or drip, but it leaks enough for you to always have a gasoline smell in the trunk.

Thanks brand new gas tank so not likely

I have the plastic tank I have it in this order: fuel tank—>rubber 2mm thick gasket—>plastic expansion tank —> metal ring
I did not put a gasket under metal ring

Does the appearance of gas fumes coincide with filling the tank? Hint
No other gasket than the one tween tank & expansion (plastic) tank.
I have seen it installed ..off.. allowing gas & fumes to escape.
The serrated ring is just to support clamping onto the plastic by the 6mm bolts

Possibly mine is installed off I will remove and check for leaks and proper install tks

No correlation to filling tank. Tks for clarifying ring

Yes possibly will check odor is around gas cap. Why did they make those lines so hard to get to danggit they needed a Dr914 on their design team at Porsche

It is possible the seal in the gas cap is torn or missing. You mentioned the tank is new. You may just need one of these -
https://900designs-container.zoeysite.com/s...steel-gas-cap-1

But it could be the seal itself. You mentioned "plastic" is should be a rubber seal so perhaps it hardened not making a good seal?

Ordered new one my original is indeed paper and possibly 46 years old?

That line pictured goes to a port on the pass side, right, of the fuel tank expansion chamber. Air from the area around the cap to the chamber. A vacuum line. The draw off port is on the other side of the chamber. What is hooked up to that port? Haynes P 56. Is your charcoal vapor canister hooked up? Eventually, that air gets sucked into the engine.

All the lines to the expansion tank are plugged. I am trying to find a canister. The small line on the right goes under the car through the tunnel and it’s plugged in the engine bay

The small line in the picture is plugged? With what? The other small port capped? That pass side port/pipe goes directly to the fuel tank. Thru the fill neck. Under the cap. Direct line to the atmosphere. This is part of the reason your car smells like fuel. Gaskets won't fix what's wrong.

Edit. The center tunnel? The interior? That small line connects to the expansion chamber. Not to something in the engine compartment. What does the line connect to once in the engine compartment? Does your car have fuel injection or carbs?

Check to make sure all 8 screws are in place. All 8 holes go through into the tank, so any screw missing will allow vapors out of the tank.

Seems to be a slight bend upwards by one screw but I would think the gasket would take care of any slight irregularities in the tank

Not my picture btw. I have FI
My small line on the pass side goes from the expansion tank to the fuel tank. The small line on drivers side goes to a black plastic line that runs through the center tunnel to the engine bay where I have it plugged. I am working on getting a charcoal canister to connect it

Picture of where I smell fuel. Yesterday lifted expansion tank off and put a new gasket. Not sure what the torque spec is for the eight bolts around the metal ring but I have them tight and the previous gasket seemed a little overly compressed form my tightening it th try and stop the odor.

I lifted the tank and checked all connections. All right and zero smell of gas at any connections or visible weeping at my all new fuel lines. The gas tank is new. The only thing I don’t have is a charcoal canister but the lines from the canister as J described one goes from expansion tank to filler neck and the drivers side line runs through tunnel to the engine bay. I traced this line and Cambodians any breaks in it.

Ideas? Could the lack of canister or fuel cap gasket be the problem? I guess I will have to wait until I replace those parts

You shouldn't plug this line. It is the vent for the entire fuel tank. If the vent is plugged, the system will find some other vent path, in your case likely past an imperfect gasket somewhere. Might explain your fuel smell.

You should prioritize the charcoal canister. When it's installed correctly, there is no fuel smell. Works really well.

Okay for now I will I plug it and make my own charcoal canister until the one that I ordered gets here thanks

I have had problems with the seal between the gas tank and the expansion tank in the past. The odor of gas developed in the cockpit and the front trunk. I loosened the eight bolts and carefully tightened the bolts, trying to get equal torque on each bolt, without a torque wrench. I tightened the bolts using a cross-pattern, similar to torqueing head bolts or case bolts. On my 76 model the bolt heads have very little clearance and it is fairly difficult to get a standard wall thickness socket onto some of the bolt heads. After a couple of attempts I was able to get a good seal and eliminate the gas odor.

I will keep trying been pretty darn careful though