New Fuel Tank and Expansion Tank
 

Well...not what I wanted to hear but I need to order a new fuel tank, expansion tank, and for safe measure a new vapor canister.

My technician removed the fuel tank this morning and there is this sticky like substance on the exterior of the fuel tank sides and bottom that isn't wet but sure smells like fuel. Its not like is smothered all around the tank as in Porsche having glued the tank in place etc. His mechanics moved the existing tank far away in the shop and my inner trunk area reeked of fuel and also has some of the sticky residue but not nearly as much as the tank itself. Odd.

I've searched here on Rennlist but cannot find any reference to others having a similar issue. Its weird and almost like the fuel tank is starting to decompose? Can that be possible? At first we thought leeching and perhaps this sticky residue is such?

Anyway off to search the internet for pricing for these items. At least now I can order the stuff and install new parts knowing we've gone through the entire fuel system.

Here's what we've done in the past to help diagnose:

1. Replaced Cap and Filler Neck
2. Checked filler tube
3. Checked cap and filler neck area for dampness
4. Checked fuel filter
5. Checked expansion tank
6. Checked and tightened all hoses lead to and away

Today:
7. Pulled expansion tank
8. Pulled fuel tank and this we feel is the culprit.

Other than what we've done can anyone suggest anything else?

Cam

I am also battling a faint fuel smell and performed all the recommended checks. I wonder if you had a leak from the filler tube in the past and it sat. Are there any indications of a crack in the tank?

No indications of a crack in either the expansion or fuel tanks. Like I said its not even wet...but even more strange is that normally when fuel dries it leaves a white residue mark...but this stickiness is just that - Sticky. Hence why we figure the tank is decomposing or leeching the fuel vapor?

Interesting. I can't imagine that the tank would deteriorate because of the fuel. Seems like something else was effected by a fuel leak or it wasn't fuel at all that attacked the tank. Could the battery acid do this?

Do you think that sticky substance could be cosmoline that was sprayed underneath the car when it was new and somehow got saturated with Gas at some point?

Cam
If you decide to replace your Expansion Tank,would it be possible for you to cut the old one open to see whats inside?I am wondering if there is something inside that gets saturated with gas and once that happens you will have gas fumes until it is replaced.
Does anyone know if there is anything inside the Expansion Tank that can get saturated with gas?

This is an interesting idea. I have also been trying to fix the gas smell in my 964. In the process I took out the expansion tank and it did have a little gas in it. Is gas in the expansion tank normal?

Yes, definitely. I saw your PM and will ask David to snap photos this week...he's away until Tuesday.

The cosmoline scenario is interesting and after David and I spoke we could attempt scrubbing the fuel tank and see if all of the crap comes off.

I know...I'm not fond of forking out $1000 but this smell is giving me a headache every single time I drive it. My wife won't even do in the car now so that tells you something.

Grrrr....

I've looked at the 964 forum for this same issue and someone there does mention that older tanks being plastic can decompose...dunno if that's true or not. However, some other interesting possible fixes have been done:

1. Check the Sending Unit and its oring
2. Vent line underneath drivers door - who knew?
3. Tighten fuel level sensor

So...armed with this information I'll rip to my buddy's shop and see what comes of it.

I'm trying to avoid buying another tank!