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1991 164S gasoline smell?

5K views 30 replies 12 participants last post by  AlfaAL 
#1 ·
My 1991 164S has a fairly strong gasoline odor after I fill the car with fuel. As far as I can tell, the car only does this when the level of fuel is at about 3/4 to full. Once pressure builds up after filling it and driving for a while, it stinks. It does it, too, if I corner hard. The smell goes away pretty much completely at about 1/2 tank and below.

I recently had the car in to my Alfa mechanic here in Baltimore to check it out. I went over it with him: no apparent stains from leaks on the tank or the filler neck; the vapor lines all seem in good condition and clamps are tight. We even replaced the gas cap (from another 164). All of the fuel lines and clamps up front are new, too. It still stinks. He is baffled, and I am baffled.

Does anyone have any good ideas/theories on how I can diagnose/fix this problem? Any ideas would definitely be appreciated!
Steve
 
#2 · (Edited)
Did you remove front wall carpet from inside trunk and inspect two molded elbows in vent system to vapor cannistor, to filler neck and top of tank?

Have you had any maintenance done to this area recently?

If nothing visible there you may neet to pull right side carpet to uncover vent tube connection to fill tube if you also can't see anything in right rear wheel well.

If still no go remove black plastic cover on trunk floor hump ove top of fuel pump cover and gauge sender area.
 
#3 ·
Thanks Steve. Yes, the first thing we did was to pull the carpet up and inspect the elbows and their hoses. They seemed to be fine.

Nope, no maintenance back there at all that I know of, and the place I bought it from a year ago knows the service record of this car well (same people are helping me work on it). We also put it up on the lift and looked in the wheel well area, too.

I'm pretty sure we also pulled the carpet on the right side, to look at the vent connection there, too.

I know we did not pull the black plastic cover off of the fuel pump and gauge sender area. Perhaps we could give that a try. Since I've had it, the car has always had an issue with the orange "low gas" light on the dash. It comes on a lot when the car is under half a tank full. Maybe I can look at that problem at the same time.

Thanks again-
Steve
 
#6 ·
Tank under pressure which is normal mode of about 2-3 psi can force fuel vapors or raw gas up around threads of tank cover especially if it has been apart and nobody installed stato-seal neoprene molded onto metal washers.

Three way vent tubing manifold is there and hooks to vent tube under there too. Higher fuel load gives more liquid under tank cover as it is stepped down in that area si fuel will be all the way up to tank cover, gasket and retaining bolts.
 
#8 ·
I was just outside with a flashlight inspecting every fuel line and vapor hose I could see and found the vent tube that runs parallel with the fuel filler hose in the wheel well had been pinched between the fuel tank and body. I followed it down. I worked that thing out and into the clear beside the tank. Maybe it will help my situation (or help when refueling). We will see, but surely it has always been like this as the tank has never been out as long as I have known the car (since '97-'98 or so). Frustrating. I even got a slight glimpse of the two short hoses at the firewall and they looked fine at least at the top of them. They are almost impossible to see without getting serious. No other signs of trouble at all.
Charles
 
#10 ·
As soon as I shut the car down today from my hot 40 min commute home I smelled fuel, so I jumped out and opened the truck (has no carpet, back wall carpet or plastic pump covers on for diagnosis) and heard a hissing sound. I had never heard it before, but I had never jumped immediately out to find the problem before either. As Steve says, check your vapor hoses. Mine was hissing from the small elbow. The two splits that it had are on the inside (where you can't see them) of the elbow in the mold seam. I have inspected this hose several times but never removed it or I would have found the small splits. I have replaced it with 3/8" straight fuel line. I have snapped a pic, maybe it will help you.
Charles
 

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#12 ·
What I tell you guys about those molded elbows. They leak when old age sets in!
 
#11 ·
God I love it!
We leave our cars half disassembled so we can figure out what's going
on.
I just today put all of the brake light components where they belong under the dash. PO fought a brake light issue for 6 years. It took me a year to diagnose it, and 3 months before I was fairly sure it was fixed.
You really need to take those elbow hoses off to inspect them because they only split on the inside seam of the elbow.
 
#14 ·
Thanks again for all of your help, guys. I am definitely going to check thise elbows again! It seems like replacing them with some regular fuel line may be the key. I will try that first.

Now...if I could only figure out the electrical issue with my trunk lid brake light that stays on intermittently. We tried to fix that, too, with no success. We replaced the little brake light circuit box that resides under the glovebox area. That did the trick for a while, but after a few weeks the brake light started staying on again. Even though I physically disconnected the brake wire in the trunk area, my battery is dead again! One thing after another......!
 
#17 ·
Make sure the brake pedal is contacting the switch. I have had to bend the mount for the switch to make sure that the brake arm actually clicks the switch, a few times actually over the years. That normally doesn't happen unless I have been doing a lot of work under the dash, it somehow gets bent out of place.
Charles
 
#15 ·
I have been chasing the opposite problem, I only get fuel smell below quarter tank and I have found no leaks at any of the mentioned hoses. I get a tremendous amount of pressure upon removing the gas cap. Especially when it is very hot outside. There was so much pressure the other day that the fuel cap was hissing, I have been switching around fuel caps. I too have been driving around with the empty of trim trunk. Never smells in the trunk however.
 
#18 ·
My brake lights we staying on and the single bolt holding the switch bracket was loose. Needed to push the bracket against the pedal arm until the lights went out and then tighten. The two switches ( one for cruise control and the other for brake lights) also thread into the mounting plate and can be screwed in to further advance the switch against the pedal arm.
 
#19 ·
Gas smell fixed, I believe!!

I have to report to you guys that I believe I have corrected the gas smell problem in my 164S. It turned out that the black plastic cover over the pump housing, hoses, etc., had worked its way a bit loose. We tightened each of the screws that hold the cover in place 3 or 4 turns each so that everything was snug. I have driven it now for a week on a full tank, and there is no gasoline odor at all.

Hopefully the problem is solved....for now!
 
#20 ·
The black plastic cover is no match for fumes, it is not airtight by any means. Now if you told me you tightened the metal fuel pump housing allen screws and that fixed the smell, I would be inclined to think you may have actually fixed the smell.
Charles
 
#22 ·
A few months back I fixed my fuel smell problem by applying some thread sealant to the bolt that hold down the fuel pump cover. I also noticed that the black plastic cover doesn’t do much so as an added feature I took a piece of thick industrial rubber sheeting that I had lying around and I placed it over the access hole for the fuel pump, I used a little spray adhesive to hold it in place and then reapplied the plastic cover. I figured an extra layer of protection from possible fuel fumes couldn’t hurt, and so far so good.
 
#24 ·
Home Depot sells statoseals that fit those fuel pump cover allen screws if you get gas fumes back again. Either #10 or 12 fit and #8 size fit smaller allen head screws for fuel level sender cover.
 
#25 ·
I found a crack in the 90 degree bend of the larger fuel vent hose in the trunk today. Hopefully that was the cause of the gas fumes.I tightened all of the mounting bolts\screws\allen screws on the cover plates while I was contorted into the trunk. Also replaced all 20 lug bolts with nice new shiney one's from Jason.
 
#27 ·
That elbow needs to be replaced or repaired with sealant that will stand up to gas fumes.
 
#30 · (Edited)
#31 · (Edited)
I bought this car several years ago from a local owner who purchased it new from the dealer in Salt Lake. He also owns an S4 beautiful green that he was not selling. So that would make the 2nd owner :) I bought it from the local want ads, I don't know if he is also on the BB... hmm just read that post... it sounds like what he told me when I bought it.. it just might be! Small world!
 
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