1973 emision stuff

[dmcummins]

I'm putting my 73 back together and I'm wondering about the lines that run from the engine to the canister in the trunk. Are they needed? When I got the car the canister was gone and the lines were just lying in the trunk.

Can I just plug the holes on the engine and cut the flexible lines off?

Also, do I need the plastic vent thing in the passenger fender?

[Jim Sims]

The '73 fuel vapor recovery (and burning - the hoses take the vapor to the engine to be consumed) system was also integrated into the fuel tank venting system. If you remove everything you may be plagued with gasoline vapors in the cab - some of the hoses (especially the translucent ones) need to stay. I would just join the two charcoal cannister hoses together. I do not know of a vapor recovery cannister or chamber on the passenger side of the '73; there is one forward of the wheel under the driver's side front fender and a smaller one in the front trunk up by the brake system master cylinder fluid reservoir.

[Grady Clay]

The evaporative emissions system is actually very useful
and worthwhile to keep in working condition. First and
very important, your 911 doesn’t constantly smell of
gasoline. If you are missing the charcoal canister, it
is common to many German cars of the era. Just tape
over the VW logo.

Here is the diagram for ’69-‘73: “

"
© Dr. Ing. h.c. F. Porsche A.G.


1) Expansion chamber [the black box under the cowl
on the driver’s side]
2) Vent chamber [behind the LF headlight]
3) Activated charcoal container
4) Engine fan shroud
5) Pressure line from fan to activated charcoal container
6) Purging line from charcoal container to engine air cleaner

Note the 13 connections around #1 and the fuel tank. This
clear (now brown) hose typically shrinks and comes off the
fittings causing gas fumes in the trunk and cockpit


Here are the locations in the 911.
“
"
© Dr. Ing. h.c. F. Porsche A.G.


With CIS the system was simplified somewhat.
“
"
© Dr. Ing. h.c. F. Porsche A.G.

1) Fuel tank
2) Expansion chamber [LF fender]
3) Activated charcoal filter [a reservoir for the fuel vapors]
4) Cooling fan shroud with hose connector [source of air]
5) Hose from cooling fan to activated charcoal filter [supplies
air to the charcoal]
6) Hose from activated charcoal filter to air filter [carries
the fuel vapors to the engine to be burned]
7) Engine air filter
8) Return hose connecting the fuel tank to the expansion
chamber [this clear (now brown) hose typically shrinks
and comes off the fittings causing gas fumes in the trunk
and cockpit]

This diagram shows CIS but the system is the simular for
MFI and carburetors from ’69 as above. The two tubes
in the tunnel are #5 and #6.


It is worth having all this stuff because some day you (or a
future caretaker) just might be required to have it functional.

Best,
Grady

[dmcummins]

Thanks, just what I needed to know.

[Eddyvdw]

THANKS!
Now I finally know why my car smells of gasoline all the time.
Ed

[Clark Griswold]

I’ve found this useful thread. Looks like my car has no evap tank in the driver front fender. The hose from charcoal canister just dumps to fender. No hoses from engine to charcoal canister. Are these hoses available to buy or do people just use other stuff?

[30westrob]

If you reference the PET for your car, all of the specs fo each hose is listed. OE type cloth branded hose is available from several sources. Rob

[Schulisco]

PET source:
https://www.porsche.com/usa/accessoriesandservices/classic/originalpartscatalogue/

@Clark: What's exactly your car? MY & model? US, JPN, CAN, CAL or ROW?

[Clark Griswold]

1973.5 911T. US car originally from CA. Went to Belgium in the 90s. I imported it from EU. So ummm US car?

[Clark Griswold]

I have pretty significant gas smell. I’ve ordered a fuel sender gasket although I remember it not looking too bad. Grady (RIP) has me thinking maybe I need to install all of these hoses that are missing to mitigate the odor.

[75 911s]

Is it the CIS setup on there "Clark"? I would still use the evap tank at the very least. I think that would help quite a bit. Adding the charcoal canister back would be more of a process, Not sure if the 73.5 had it in the back like the midyears or not, I think it did.

[Clark Griswold]

My 73.5 is CIS yes. I’m not sure what you meant by set up? There is a charcoal canister in the trunk.

[Clark Griswold]

Upon further inspection I have a fuel leak. Guess that explains it. Above the base of driver side torsion bar.

[E Sully]

The lines and expansion tanks are to vent the fuel system and contain and burn excess fumes. There are no negatives to the system. While some items are different for 74- on, the main ones for '73 are:
Front fender tank 3. https://www.pelicanparts.com/More_Info/91120107300.htm?pn=911-201-073-00-M253&bc=c&SVSVSI=4247
Under cowel in drivers side frunk 2 https://www.pelicanparts.com/More_Info/90120106222W.htm?pn=901-201-062-22-W-M253&bc=c&SVSVSI=4247
Charcoal canister 6 can be found used: 911 201 183 00