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1987 Alfa Romeo Graduate.

When I drive the car for a while, I smell gas in the passenger area.
The smell is most pungent in the trunk (after I get out and smell in there.)

Are there any common problems that cause this to happen. I know that by pulling up the carpet there, one can get into the gas tank. Any suggestions on what to check first?

Thanks,
Rich
 

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Hi Rich -

While my Alfa is thankfully fume free, I've seen this problem come up a bunch of times on the forum - I think if you do a quick search you'll find lots of info pertaining to your questions.

I know there's a bunch of stuff you'll want to look at. It could be fumes, or it could be leaking gas.
 

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It is very common. If you do a search you will find many forms addressing the issue. You want to make sure the seal of the gas tank where the gas filling hose/pump/float mechanism goes into it is good, that the hoses are not leaking and that there isn't a hairline crack in the tank itself. The tanks flex from the gas over time and develops cracks on the bottom and I even had one around the return hose connection on the top. These are just some of the common problems. Sometimes you can place paper first aid tape around the hose connections and see if they become saturated to track down leaks. But remember, it's gas so use all precautions.

I spent a few months tracking down leaks at the beginning of the year. I started replacing the hoses and seals after repairing a bottom side tank crack. Then it turned out there was also the top side crack - probably caused when bottom one was out being repaired. If you need an almost new filler hose, I have one on e-bay (I know, shameless plug, but it's an easy way to start)
 

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I have the same problem in my 91 Alfa Spider and really should get around to fixing it... Anytime i put clothes in my trunk, I have to wash them again before I can wear them. :p

If you figure out your problem, let me know what you're going to do to fix it. I'm guessing it may require checking the fuel pump and tank on my car... I think the fuel pump has problems because it tends to whine... worse when low on fuel, but whines no matter what...
 

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The gas smell is pretty common on these cars. My 87 Spider had the problem. The clamps on the Filler hose were loose. I could actually see the gas seeping from the hose connection. Even a little seepage can smell to high heaven.

Dave
 

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Yeah, mine has really only had odor in the trunk and it's never been anything I've really been overly concerned with as it doesn't smell that strong (clothes just tend to suck up the smell really well).

It's also not an issue while driving -- i can't smell any gas or anything so I'm not worried about it...

I've heard it's really common also -- but it's still something I'll get around to fixing eventually.. I'll have to check some of the hoses on mine as you suggest.
 

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Haha. :) I very much hope it doesn't cause you or the Spider problems either. That'd be very unpleasant.

Mine is the same way... Worst right after I fill up... But, I really don't think it's anything to worry too much about -- more of an annoyance since putting clothes in the trunk is basically not a good idea.

However, girls seem to always be really worried about it and I just shrug it off... It's an Italian car -- it's supposed to smell like that. :)
 

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Hey all... each of you with the smell needs to pay more attention to it. It's not the gas(liquid) that ignites..it's the FUMES. If you drop a match into a barrel of gasoline it would go out (if you could get through the fumes). Smelling gas is never a good thing... getting rear ended could be lethal.

If you smell gas ... find it and FIX it.
 

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But Mad North-Northwest
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The yellow thing is the check valve that lets air into the tank. If you pull it off, you should be able to blow through it one way (such that air would go into the system). The white disc-shaped valve is more likely to be the problem...that's the check valve that lets air go forward to the carbon cannister. Sometimes they get sticky - you can pull it apart and clean it to fix this. Make sure you put it back on in the right direction.

Box on the right is the airbag control unit, gamebrowser.
 

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I had the same problem on my 87 - I replaced all hoses and stuff, but at the same time I put on a downturn pipe. Well now I'm starting to get curious...

Is it necessary to put a downturn pipe on a S3? The rubber spoiler is there, making it different from say a roundtail...I was considering putting a straight back pipe again, but I'm not so sure if that would put odor in my cabin again...and I DID replace the hoses at the same time as the downturn, so I have no idea which one did the fix...my guess - it was the hoses.

does anyone out there have an S3 with a straight back exaust tip that doesn't get any fumes in their cabs? I know it came that way (straight back with a diagonally cut tip) stock...I'm just trying to be cautious :)

thanks,
Joe
 

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But Mad North-Northwest
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Yep. As the fumes expand in the tank, they'll come out through that check valve into your trunk. You should be able to get a replacement from Alfa Parts. You could also just try spraying carb cleaner into it and then blowing it out with compressed air..most likely it's gummed up with polymerized fuel.

You sure there's no other check valve there? From previous conversations I was pretty sure that the system on an '87 was the same as my '91. Look in msiert's photo above...behind his hand, you should see part of a white, disc shaped check valve. It's inline with the hose that goes forward to the front of the car.
 

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Although the valve seems like the obvious place for a leak because it is the only open part of the system, most leaks I've read about on this board or personally experienced come from other areas. Certainly worth checking due to the ease of doing so, but I doubt it's your problem.

Putting the car on jacks may make it harder to locate the leak. Try my paper medical tape method if you can drive it around and get the gas pressurized and sloshing. Wrap the tape at the ends of the hoses and around the top tank seal. You might see the paper absorbing the gas and determine where it's coming from. It's VERY hard to see small leaks just by looking for them and the tape absorbs and shows better, usually clear at first, it turns brownish after a day or two. Or if you aren't sure the tape is wet, try smelling it when you take it off or run your finger over it. If the car is on jacks you'd never find these. The jacks will help if the leak is under the car, but you may still need the system more pressurized from driving before it will appear.

I assume you've inspected the hoses and tightened the clamps.
 

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msiert said:
Dumb question but but what hose's? The vent hose's in the trunk I asume?
The bottom of the large filler hose, and the return hose (there may also be some clamped connections where a hose connects to another hose here also). I think there may be another one in the area too. Just pull back the bottom and side carpet in the trunk. If there's a hose eventually connecting to the top of the gas tank you want to check it.
 

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If you look in the repair manual for the 87s you will see a diagram for the evaporative control system. Page 04-9.

Briefly, the plastic tank is basically a condensing tank for fuel vapor. We don't want any hydrocarbons to evap uncontrolled into the air. Therefor any expansion in the fuel tank due to heating, etc. must be vented through a charcoal cannister up in the right front of the car. So, there's the vapor line going from the fuel tank filler pipe to the plastic expansion tank. From there a tube exits and goes to a "T". There are two valves, one on either side of the "T". One (the yellow one in the pix) is a one way check valve IN. This allows fresh air INTO the tank only to compensate for varying air pressure . . . such as when you go from the top of a mountain into a valley. This prevents a vacuum from forming in the tank and restricting fuel flow out, or even collapsing the tank. The other valve (the white one in the pic) has a tube connected to each side of it. It is a one way check vavle OUT. Any excess pressure in the tank (heating, or say going from the valley to the mountain top) is allowed to pass through this check valve and proceed up to the front of the car into the charcoal cannister, and from there to get sucked into the air intank and burned. It's a one way check valve because if there's negative pressure in the fuel tank, we don't want to suck anything from the charcoal container . . we want fresh air from the trunk to go through the other one way check valve.

Now, that said, there are several sources of possible fuel smell. Keep in mind that it only takes a minute amount of fuel to evaporate and cause a fairly good stink. Check:

1. All hoses. Check for cracks and bad clamps on fittings.
2. Crack in the plastic evap tank.
3. Seepage around the filler neck pipe unions
4. Seepage from where the fuel gauge sending flange mates to the fuel tank (most likely IMHO).
5. Bad fresh air one way check valve.
 

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But Mad North-Northwest
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Well, there's basically a few ways for the system to fail and leak fumes. Obvious one is a loose hose connection somewhere, so like 90Quad said that's an important thing to check and he gave some good tips. Also make sure that the gasket at the top of the fuel tank (where the sender unit is) is intact and the six screws are tight.

Another way is for the air inlet check valve to fail. Never heard of that happening before, but this is apparently what happened to gamebrowser. If it plugs completely you'll get a rush of air into the tank when you open the cap, if it lets air flow both ways you'll vent tank fumes directly into the trunk.

Another way is for the flow forward to the engine to be blocked, causing a pressurized tank. Even with tight hose connections, this will stink up your trunk something good. This can be either (a) a stuck white disc check valve, (b) a pl ugged carbon cannister, or (c) a non-operational purge soleniod in the engine compartment (Motronic only...don't think the L-jet has this). Obvious symptom of this one is a rush of air out when you open the gas cap.

When I had this problem a few years back, it was a combination of (a) and (b).

Msiert: yes, you can probably use any generic check valve, but the Alfa one is inexpensive and still available last I checked.
 
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