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Topic: Gas smell with full tank

in Forum: C3 Fuel, Emission Control, and Exhaust Systems


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Gas smell with full tank (5/15)
 11/20/03 12:43am
debrown
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Mammoth Lakes, CA - USA

Vette(s):
1971 LS5 Convertible with M/T, A/C,Brandshatch Green, Saddle Leather interior, numbers match


Joined: 11/15/2003
Posts: 37

I just recently joined this group, and I don't know if you still have the problem or not,but I had a gas smell when I had a full tank and/or turned corners that caused the gas to slosh in the tank. I discovered gas had leaked out a separator assembly, which is a small black plastic box containing a check valve and mounted on the driver's side of the gas tank. It's connected to the return line from the fuel pump and to the fuel tank by rubber hoses.

In my case, the separator box was leaking at a joint in the box, leaking gas down on the exhaust muffler (and could have been a major problem). So I removed it, after first removing the spare tire container, took it apart at its joint, cleaned it and reglued it with a gasoline resistant glue.

It hasn't leaked since.

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Gas smell with full tank (6/15)
 11/20/03 1:38am
ricknhis69
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Does anyone know if a '69 has this?

|headscratch|

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'69 350/350 conv.

Gas smell with full tank (7/15)
 11/20/03 10:10pm
Mr69Vett
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DE PERE, WI - USA

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1969 350, 4-spd, 3.53 gear, side exhaust, custom mix yellow PPG base/clear Brilliant Yellow


Joined: 12/9/2001
Posts: 231

Rick, I just looked thru my assembly manual and yes there is a gasket between the filler and the neck. I have a part # 0f 3826417, not sure if that will be a good GM number though. Looks like there are 8 bolts from tank to filler neck. Good Luck.

Dave
Mr69vett |smokin|

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Gas smell with full tank (8/15)
 11/29/03 4:42pm
Paul Borowski
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Massillon, OH - USA

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1968 International Blue conv 1968 Silverstone Silver coupe 1974 Orange coupe 1975 Silver coupe 1980 Yellow coupe


Joined: 1/20/2003
Posts: 6

rick, only Corvettes that had the "charcol canister" had this 'black plastic seperator". They vented to a 1/4" steel line that ran along the driver's side frame rail to the charcol canister. The car's that also had these charcol canisters had "SEALED" gas caps(late '71/'72 |headscratch|). You may have such a small leak(like happened with my '75)that you'll only smell the vapors and NOT see liquid. Could be as simple as a loose or rusted fuel line clamp, to a very, very small age crack in one of your rubber fuel lines, either supply(the larger one) OR your return(smaller line).
Gas smell with full tank (9/15)
 12/11/03 1:13am
ricknhis69
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Paul, I agree that it only takes a small leak to create a lot of fumes, but, why does it only happen over 3/4 of a tank? I would think that if hoses where the issue I would have an odor regardless of tank level.

Once the level in the tank drops, there is no smell at all.

|headscratch|

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'69 350/350 conv.

Gas smell with full tank (10/15)
 3/17/06 1:09pm
Adam WartellLifetime Member
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Eagleville, PA - USA

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Used to own a 1979 Corvette now owned by JB79


Joined: 11/1/2001
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So, I just did a search on "Gas Smell" here and found this thread.

My 79 does the same thing, and it is in the shop right now for that very reason.  The mechanic did in fact determine that the tanks leaks at the top when full.  I still have to speak with him directly, in about an hour.  I will reply again when I get more detail. 

One of the things I want him to be careful about, is looking for a build sheet!



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Gas smell with full tank (11/15)
 3/17/06 2:45pm
warbird
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Roseland, NJ - USA

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1974, 454 with 4 on the floor, matching numbers.


Joined: 12/4/2003
Posts: 966

I had the same problem on my 74. I replaced the fuel cap which was bad, but the main cause was the over flow hose which was cracked at the top by the fill spout. It never leaked enough fuel to leave any sign of a leak, but it did emit a strong gas smell. Fixed the hose, no more gas smell,  
Gas smell with full tank (12/15)
 3/17/06 11:01pm
Adams' AppleLifetime Member
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Duncanville, TX - USA

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#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas


Joined: 11/8/2003
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The filler neck on the later cars(77-82) were sealed by the "Bladder". It formed the seal for the neck, as well as being the bag for the fuel tank. If it is leaking at the filler neck/tank junction, chances are the bladder itself is bad. The good news is, you can completely remove the bladder, and seal the neck with a cork gasket, like the older tanks were.

This is a pretty old thread!! That "search" function is purty neat, eh Adam??

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Gas smell with full tank (13/15)
 3/18/06 6:38am
dwright
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Victor, NY - USA

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2004 Commemorative Edition Coupe, Auto w/HUD. 13K miles in 2015. Sold 1982 Red Coupe


Joined: 7/12/2004
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If you are going to replace the cap, consider a locking cap. With the price of gas always going up, I wanted to make it more difficult for the gas robbers.

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Gas smell with full tank (14/15)
 3/24/06 11:14am
gs77vet
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Joined: 3/19/2005
Posts: 385

be sure you do not over fill, if you do you might get some splash back around your gas cap. that makes a nasty gas smell.gene gs77vet38800.3441550926
Re: Gas smell with full tank (15/15)
 12/26/17 10:47pm
Pberns
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Camano Island, WA - USA

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1969 427 Coupe


Joined: 6/9/2017
Posts: 2

My sending unit gasket was leaking changed it out and the smell went away.

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