GAS FUMES AFTER FILL UP...

[creekman]

I'm getting gas fumes in the garage, but nothing on the floor.  I've made sure that the cap was turned tight or it had ratched tight..  Is it possible that the charcoal canister is bad?  I might add the fumes are easily detected, but not overwhelming...

 

Thanks,

 

Mitch

[judgejon]

Hi Mitch.  Check out some of the posts re the vent valve on the fill tank.  I wonder if fumes could escape if it's somehow stuck open.  I think the usual issue there is if that valve doesn't open to allow the tank to be filled.  But it's a thought.

[creekman]

Thanks Jon...  First off I can see you're a man of many interests and good taste, whether marriages qualify I don't know, ask me how I know.  If I remember you get to the valve by removing the trunk upholstery on the passenger side?

 

I hit the search button for fumes, without any success, I'll follow up as you suggest...

 

Mitch

[judgejon]

Yes, I recall you go into through the right side of the front end, right at the fill tube.  good time to fix that little plastic emergency opening pull as well.

My issue was a wire chewed up by a mouse that had built a nest right on top of the fuel tank.  Had to take out battery, and everything around it to get to the spot.  Decided to go from top down.  Took 2 min to fix the wire. Problem solved.  Valve opened.  Took $750 in labor to get to it.  Really.  The thread is out there on the forum somewhere.

Good luck on this.  Not sure where else the gas fumes could be coming from if not from the filler pipe area somewhere.

Ugh, use a flashlight, ok?  No matches.  😉 Cheers.  Be well, j

[356to966]

In my case, the gas smell came from a hair line crack on top of the nylon fuel level sender unit.
Its easy to check. The top of the sender is exposed when you remove the access panel located under the battery.

[creekman]

356, Good suggestion, that might be a good place to start... It's not under the plastic dome in front of the battery?  I don't know if my wide body trunk layout is the same?  I had a '53' BeeHive coupe, 'Yr.? Cab,  '58' 4 cam speedster, '64' SC.  If we had some of these older cars back we would be sitting a little higher on our wallets.

 

[judgejon]

Totally agree.  

Had a fuel gauge sender issue in my '79SC.  So... get new sender from Sunset, open hood, pull back carpet and thin cover piece, and there's the fuel tank.  Out with the old sender, in with the new sender, and all done in about 10 minutes.  Back in the day.....

That's a great photo of a good looking 996.  2003?  Headlamps are end of 996-model style.

Cheers...

[creekman]

Might be an easy place to start, although I replaced it about 4 years ago.  I'll give a close inspection and go from there.

I replaced the bumper cover with a modified 997 GT2 bumper cover.  It was an aftermarket fiberglass piece.  It was so far off from fitting, not even close.

I already had the wrong one sold to me sold to me by another dealer so I was a concern buyer, the guy swore it would fit.  I probably have over 40 hours in fiberglass work to get it this close.

The big advantage is for the 3rd water radiator to have good flow through air...

 

Plus, I like the LED DTR lights....   Also, I have 3 front directional lights, 1 in the headlight unit, the LED DTR light has an amber turn signal light and we wired

up the fender side marker light to also be a directional light.

 

Thanks all for your help...

 

Mitch

[judgejon]

[judgejon]

Trying to post a pic of my 996C4$

A8550697-902C-416E-8DAD-93E4B35040C9.heic

Edited April 29, 2020 by judgejon

[creekman]

I love the looks and hips on the wide body...  I had a '84' Turbo Look, with original paint to sample, but got tired of the whales tail.  I think the 996 

is a great design and will hold it's looks for a long time.  After all the test of good design is how will it age and look 10-20 years out.  I think the 996 will do well,

it checks all the boxes for me.

 

I see you're from CA, where is Mendonesia California...  LOL

[judgejon]

Up on North Coast.  Mendonesia is a locals name from about 40 or so years ago.

We have family out in Pecos and Terrell Counties, TX.  Have you ever been to Sanderson?  Dryden?

 Sorry, I tried to post a pic of C4$ but it didn't open.

Edited April 29, 2020 by judgejon

[creekman]

The fumes went away, now there back with a vengeance...  I changed the gas cap which was cheap and worth a try, what are the possible choices?

 

1.  Per 356, check for hairline cracks in the gas tank sending unit...

 

2. Per Judgejon, replace the check valve behind the right side fender liner.

 

3. Could the charcoal canister be full.  Where is the charcoal canister?

 

4. Can this problem be identified with my Durametric program...

 

Thanks, all replies will be appreciated...

 

Mitch

 

[JFP in PA]

The EVAP cannister and associated valves in the wheel well by the gas filler neck:

 

[judgejon]

I’m pretty sure you would have seen any gas leaking out from small cracks in hoses.  Maybe worth another check for worn hoses, wet spots, etc.  Mystery for sure. 
Good luck, Mitch. 

[creekman]

Jon,  That's a good idea to step back before throwing a lot parts at the car.  I have my T-Bird restomod project on the lift right now.  To do it right I need to drop down the belly pans for a good once over.  

Speaking of belly pans...

Here's a tip if you're tired of replacing the belly pan brackets/retainer clamps.  I used aircraft loose nut plates and riveted them to the braces.

[creekman]

I put the car on the lift and removed the belly pans...  I was hoping that would find the source of my stinky gas smell once the belly pans were removed.

Nope, no stains on the belly pans and no wet hoses.  So I guess the next step is to check/replace the fill pipe check valve and or the charcoal canister.  Can anyone tell me if the check valve is stuck open will the car run fine and could be the source of my gas fumes...

 

If there's a problem with the check valve will it show up on my Durametric program?

 

Thanks,

[JFP in PA]

11 hours ago, creekman said:

I put the car on the lift and removed the belly pans...  I was hoping that would find the source of my stinky gas smell once the belly pans were removed.

Nope, no stains on the belly pans and no wet hoses.  So I guess the next step is to check/replace the fill pipe check valve and or the charcoal canister.  Can anyone tell me if the check valve is stuck open will the car run fine and could be the source of my gas fumes...

 

If there's a problem with the check valve will it show up on my Durametric program?

 

Thanks,

 

Unless something codes, Durametric won't see it.

 

Before ripping the car apart, open the front trunk, remove the battery cover, and have a sniff about; we haven often see problems with the top area of the fuel pump assembly involved with gas odor issues.

[creekman]

Thanks, I appreciate the direction, I'll give it a shot.  

[judgejon]

Another thought.  Can you access the fuel tank on top where the sender goes in?

i remember changing out the sender on my ‘79 SC.  Easy job then, not sure on 996, but maybe there’re a gasket or something that’s cracked?  The filler switch wires are under the battery tray.  I don’t think you would get too much odor from filler check valve, as problem there would be more likely not opening to allow a gas full up.

I remember a mouse nest up under there once, chewed through the check valve wires.  it’s on the forum somewhere. Valve wouldn’t open, but a quick solder job on wires was quick fix.  Problem was the time to access the switch under battery tray.  Seemed lots of stuff had to get moved out first to get under there. 
Keep striving.  Good thoughts...j

 

[Loren]

Lots of places for potential fuel/fumes leaks. And, yes the tank sender unit is plastic and it can crack.

 

[creekman]

7 hours ago, JFP in PA said:

 

Unless something codes, Durametric won't see it.

 

Before raping the car apart, open the front trunk, remove the battery cover, and have a sniff about; we haven often see problems with the top area of the fuel pump assembly involved with gas odor issues.

 

[creekman]

2003 996 C4S

 

JFP, Jon and Loren...  many thanks for the support and direction.  I removed the battery and panel all looked good, I also removed the top hat cover next to the bulkhead on the trunk side, again no tell tale signs of cracks there either.

 

I guess next will be to look at the charcoal canister and gas fill check valve.  I think I'll change out the charcoal canister first. 6 years ago when I installed the LS3 V8 I had a problem connecting up the charcoal canister to the new conversion.  A friend of mine from the airport holds certificates on welding, A/C, Electrical, Diesel engines on unlimited tonnage for ships.  He's a civilian contractor hired by the navy to be in charge of maintenance on big ships...  Where he goes is always a secret.  This guy will always be the smartest person in the room... Anyway the Porsche might still be sitting in the garage if he hadn't figured out how the system worked.  Took him 30 minutes to draw out the system and 10 minutes to change some hoses.  But the charcoal canister had been full of gas, but the system has never given me a lick of trouble since, so long story short, that is why I might start with the canister...

 

Loren, say again how you assign points...  Thanks