3.2 Evap System Schematic & Physical Locations

[Quasimoto]

I only have this basic schematic for the Evap control system on my 3.2, but it seems to be enough to enough to follow things around. I am trying to track down the hose connecting #4 (Evap Chamber) to #5 (Carbon Canister)

Once it leaves the top of the Evap Chamber it passes thru a steel bulkhead connection into the trunk just below the fuse box.
From there it is a 4mm hose that drops into the crack between the tub and the fuel tank, and I loose the plot on how it gets back to the engine bay.



I am trying to locate the nipple where Item #17 is in the pic below. Does it get into the tunnel somehow? If so, is there a diameter change somewhere along the way?



Also, I think that hose #13 in the pic below is the inlet to the Carbon Canister, and the larger hose #17 is the one that connects to the Air Filter Housing.
Is this correct?



Apologies for the stupid questions...just thought it might be easier to ask rather than keep searching for possibly the wrong thing... ;/

[sparkysvega]

The hose between evap tank and charcoal canister leaves the frunk and and goes under The pedal floor board to a steel pipe into the tunnel and comes out next by the clutch cable and fuel lines . You are correct about number 13 and 17 of the charcoal canister . I can’t help with number 17 , I’ve never looked for it .

[Quasimoto]

Thanks, I’ll pull up the pedal board and continue the hunt!

[Quasimoto]

Like many that have gone before I am chasing the elusive faint smell of fuel in the cabin after the car has been sat for a bit...

So I dug around and found where it enters the tunnel behind the pedal board. It’s the little 4mm hose left of the larger brake vacuum fitting.


I expected to find maybe a loose connection, or possibly a cracked piece of old rubber, but no joy. (also never found anything that looks like the #17 boot)

What I did find was a chafed spot in the metal tube that maybe has a pinhole or crack. Going to fiddle with it again tomorrow and see if this could be it...fingers crossed.

Pardon the dirty floor pan...

[brianlay]

mine had leaks in the cloth/rubber hoses associated with the filler and the overflow container. Also had a hairline crack in a weld on the stainless filler neck

[Quasimoto]

How did you repair the crack in the filler neck?

The cloth hoses on my Expansion Chamber were a bit smelly so I’ve replaced them.

Trying to locate 4mm x 1.5mm cloth braid tubing to replace some of the small lines, but only finding 3.5 and 4.5.

Is there a source for the 4mm, and if not what’s the closest substitute?

[brianlay]

Initially I used some epoxy covered with a rubber patch held in place by aero seal clamps.
Later I replaced the whole filler pipe.
My current problem is the steel line in the tunnel is blocked by rust about a foot into the tunnel.
My plan is to bypass it with rubber line in the tunnel.
Currently the tank is vented to the atmosphere in the front fender.

[Quasimoto]

Makes sense...

I've temporarily patched my apparent leak on the tunnel tube with a gasoline compatible epoxy. If that cures my smell, I'll have to pull the pedal cluster and do a proper fix, but at least I'll know what needs done.

[Pedro '84 Coupe]

I was able to find some 4 mm braided hose at a local vintage VW shop. Belmetric also carries braided fuel hose in 4 mm but I haven't tried that. Crazy how much Porsche wants for that hose!

As far as the gas smell, I fought with it in the cabin for a few years. Had a leaky fuel pump and changed that with a new one. Still had gas smell in the cabin. I replaced every fuel line (except tunnel lines which are still OK), hose and gasket in the evap system and fuel tank, including the expansion tank but still had a whiff of it. My mechanic did a smoke test and found a leak where one of the DAPOs drilled holes in the top of the tank to mount an amp. Smart, huh? We plugged that up with some epoxy and it seemed to help but there was still the darn gas smell in the cabin.

A few months ago I decided to remove the gas tank to see if I could get the epoxy repair welded. The seams where the two halves of tank meet were badly rusted too but I was hoping that also could be fixed. Couldn't find anyone in town who would work on the old tank so got a new Dansk tank and an inline filter kit (Len Cummings). Now the gas smell is completely gone. The odor could have been from the epoxy fix or the rusted seams but the new tank solved the issue. I'm not saying this is where your gas smell is coming from but it might be worth checking out.