Targamike

During my first DE event a few weeks ago in my 1990 C2, my instructor noticed a fuel smell (I was too elated to even notice!)
He told me they changed the fuel filler neck after 1990 or 1991 and many people replace them in the early 964s to get rid of the smell.
My concern is not so much the smell as the danger. Is there any chance of a problem with the fuel vapor in the same compartment as the battery?
I will eventually replace it but hate to spend the money right now if I don't have to - it has been this way for 100k miles after all.

Bill Wagner

Michael:

Yes, this CAN be dangerous, but probably not in the way you're thinking.

The problem with the old filler neck is that it warps internally so that it's no longer circular. The fuel filler cap gaskets fail to make 100% contact in this case. As you go around curves at moderate or high speeds, because the cap is no longer seated, fuel will come out of the top of the cap. Under what amounts to racing conditions, the fuel will actually start running OUTSIDE the car. A guy at Virginia International Raceway had this problem so bad that the fuel was apparently running down the side of the car onto the tires and he lost traction and crashed his car. This is (or was) documented on the PCA-potomac region web site under the 911 discussion group a few years ago (if I recall correctly the title was something like "Incident at VIR"). Their web address is <a href="http://www.pcapotomac.org" target="_blank">www.pcapotomac.org</a> if you want to search for it (it was a few years ago, so maybe it's not there anymore).

Aside from that, even in "normal" driving, what happened to my car is that the gas would leak into the fuel lid compartment and then slowly drain down into the carpetted front trunk area, which left the trunk smelling like gas. Replacing the filler neck fixed that problem but the area still smelled like gas until I actually pulled the carpet and cleaned it. A LOT of the odor seemed to have accumulated in the front pocket where a plastic tire change bag was stored.

The filler neck is about $100, and the job doesn't take long. I let my dog do it because he was bored!

jonfkaminsky

And don't forget the deteriorating rubber connection hoses with the micro-fine cracks that continually leach vapor. I have replaced my neck (no more pooling fuel in compartment), cleaned my carpet, etc. Fuel odor always comes back, and in an accelerated manner during warmer temps. This tells me the increased pressure in the tank increases the rate at which the vapor leaches through the rubber (my theory anyway). I have never observed anything wet or otherwise visible in my trunk area. But, my nose tells me that the hoses reak of gas.

Bill Gregory

I changed the rubber seal on the gas cap, which cut down on some of the odors. Part # 944.201.553.00, around $3-$4.

horst

Bill, been feeling lazy, and have not visited the trunk area since last concour many months ago. This fuel filler neck is probably needed in my car. 1.) source? dealer only or cheaper some place else? 2.) do you have a diagram or instructions on how to replace/ I could probably figure it out, but as I just said, feeling lazy today, and lots of honey-do's including servicing the house a/c, lawn, etc., etc. have priority

Bill Wagner

Horst:

I assume you're talking to me, but if not, then my I hope Bill Gregory will forgive me for butting in.

I don't have a diagram, but there may be one at AllData.com. You really don't a diagram though, it's just common sense really.

First off you obviously don't want the gas tank anywhere near full. Disconnect the hoses in the trunk that attach to the filler neck. Take the gas cap off, and you'll see a "C" type clamp that you take off with by spreading them like a piston ring. This pops off and then you pull off the gaskets. You have to sort of snake the fill tube out from inside the trunk, and then just reverse the procedure to install the new one. About the only caution is to be sure not to overtighten the hoses connecting to the new filler neck because you may crack it.

The other posters have good points (Bill Gregory and Jon). Rubber likes to deteriorate with age. When I tried to fix mine by getting a gasket for the cap (which I did before hearing about the filler problem), my Porsche dealer said they didn't sell just the gasket and could only sell me a new cap, which was about $15.00.

I should also throw out for anyone else with a gasoline odor problem that this is only one of many possible causes of gas odor. It could be a real leak in a line somewhere, so the problem should be isolated. With my car it was pretty easy to do. With the gas tank full, if I took the car down a twisty road so the gas would move from side to side in the tank, and then stopped the car and got out and checked underneath the the fuel lid, gasoline would be pooled up in the little compartment where the gas cap is. The problem persisted even after using a new gas cap, and then I heard about the filler neck problem. That fixed it for me.

Hope this helps,

Bill Gregory

There's a nicely done article, by Mark Schettenhelm and Luis Arisso, on tech.rennlist.com under 911 engines with pictures and diagrams on how to change the filler neck.

horst

Thanks, guys. Thank God I don't have to rely on common sense, as Bill W. suggested. I just ran out. I take it this item is a dealer only item, and about $100? If the gasket under the fuel sending unit is like on my 930, that would also probably be a good thing to replace at the same time. I assume also that the PNs of the associated connecting hoses are shown on Alldata? (BTW I am not a suscriber to this- can I get the info anyhow?)

jonfkaminsky

No the part numbers are not included with this TSB as shown below:

Filler Pipe - Fuel Odor
Group2

Number
9401

Model
6 Cyl.

Part Identifier2007

March 10, 1994

Subject:
Fuel Filler Pipe

ATTENTION: Service Manager / Service Technician

Models Affected:

911 C2/C4 all
911 Turbo 1991-on

Concern:

If a customer complaint of fuel odor is reported, first check all connections on the fuel tank, filler pipe and cap for tightness and proper sealing.

Pressurizing the fuel tank with approximately 3 PSI and using an electronic hydrocarbon detector will find very small leaks which may be possible on the top of the filler neck or on the hose connections. If the fuel filler pipe shows signs of leakage in these areas, it must be replaced.

General Information:



If the fuel filler pipe is found to be leaking, only the fuel filler pipe with a metal band at the top should be used for repairs.

Parts Information:

Description Part Number
Fuel Filler Pipe 964 201 043 03

Warranty Information:
(if applicable)

Damage code: 2007 50 0002

Labor Operation Description
2007 1900 R&R Fuel filler pipe 30TU

Here is the exploded view of the entire fuel tank and filler neck system:




Hope this helps...

Bill Gregory

Jon, thanks for posting the TSB.

The current part number is 964 201 043 06. Read the article on tech.rennlist.com. The authors did a very good job comparing old and new and showing via pictures how to complete the update.

Bill Wagner: Part 21 in the TSB is the gas cap gasket that your dealer wouldn't sell you.

horst

Thank you.

jonfkaminsky

I guess I should have said something about my post- I added the exploded parts diagram. It is not part of the TSB. The upper diagram showing just the filler neck is part of the TSB however.

Arjan B.

Hi there,

I asked a sort of question last month in a topic, and looking at the picture of the tank and tank parts, I notice that my filler system is different.

Parts with number 6 and 17, the fill hoses, are different.
Part no 17 is a plain hose, no accordeon forms in it. Should this be a already replaced hoes??


Arjan
964 C2 1992 Black <img src="confused.gif" border="0">

MSchett2

I am glad that my article has been useful. I would like to add that the filler neck is not a dealer only part. It can be obtained from many different Porsche parts suppliers. I sent e-mails to several with the part number and went with the lowest price. I think it was just under $100. I was able to purchase the gas cap gasket from the dealer for around $5.

horst

May I ask where you endent up buying the pipe from?