rhett838

I have a convertible, but when I'm done driving I smell like gas fumes. At first I thought it was just part of owning an old car, but I think the fumes are really more powerful than the should be. Even my dog smells like gas when he goes along for the ride, but that's an improvement for him.

I can't really smell it while I'm driving, but while I'm stopped or at a light, or esp when I put it in the garage, the fumes get so bad my eyes burn.

I would bet the canister hasn't been changed in quite some time, but is this where my problem lies, or could it be something more complicated, like the gas tank, fuel lines, carburetor etc?

Thanks for your help!

Allan R

Did they even have a charcoal vapor cannister in 69? I thought that only came into being after 1970??

rhett838

I don't know...

I feel silly asking questions that are probably simple to most. I have an assembly manual to help me with thngs like this, but I think I'd be better off trying to decipher the dead sea scrolls. I got the manual from Fusick, but it's hard to read, and for me it's hard to follow. There's no index, or table of contents. Couple that with blotchy lettering and I can't find anything!

So the Classic Oldsmobile is the only hope for an extreme novice like me!

cutlasssupreme71

Hi,

From what i can tell is, in my 71 supreme the vapor canister was mounted behind the headlights on the passengers side at the radiator core support....

I dont know when they´ve started to put them in the cars....

There could also be a gas leakage somewhere .....

Regards,

Torsten

yzzerdd

Assuming you've traced your lines and don't have a leak, could it be your gas cap not sealing right? Does this happen no matter how much gas you've got in the tank? Also, while sitting at a light(or driveway, whichever), and giving it a good amount of gas, do you still get the strong fumes? If so, I would bet the fumes are still there when driving, but well ventilated. If the fumes are so bad your eyes burn, I would not drive the car until you find the problem. Remember, its the fumes, not the liquid gas that are most flammable. Someone tosses a cigarette out the window while you are at a light and your car will be up in smoke.

--Ryan

joe_padavano

The evaporative system (charcoal canister) was not used until the 1970 model year.

rhett838

Thanks Ryan...

It happens all the time, no matter how full my gas tank is. My eyes burn when I pull it into the garage, not so much at intersections, but the fumes are still noticeable none the less. My Garage has a VERY trace amount of gas smell, but I always thought that was just b/c the walls soaked up someof the fumes.

Maybe problem is worse than i thought...

Thanks to all for your input!

1969w3155

Start looking for leaks in your lines and your gas tank. My '69 had the same problem, the seam in my gas tank started to rust out. Replaced the tank.

Lady72nRob71

Gas fumes inside the car are abnormal.
The early 70's cars used a liquid-vapor separator can located behind the rear seat as shown here with :


From the bottom, under the car, there are 3 or 4 vent lines connected to the gas tank. See if you have this. Check those rubber lines, as often they are neglected and they crack open. Not sure if the 69's used these or not.
Also check for rusty areas or broke seams on the tank itself.
I would advise to do all this outside, windows and doors open, where the wind will disperse the fumes.

Study up on the 'fuel' section of your manual, to see where the gas tank is vented and how.

I am assuming there are no rust holes in the floors or trunk where exhaust fumes are entering and that the exhaust pipes / muffs / manifolds are not leaking and exhaust is discharged at the rear like they should be.

Jamesbo

I would see if there is a seam leak or a leak where the neck goes into the tank. Around here you can drop the tank and take it to a radiator shop to be cleaned and sealed.

alsip455

you may have a hole in the top of the gas tank which will release vapor dont light a match in that garage if you smell vapor you can smell the differance between raw gas and vapor let off from the gas good luck

Yellowstatue

'69's like '68's don't have a vapour canister...so while the engine is running and the hood is up of course look at the fuel filter fitting on the front of the carb and you will more than likly see it leaking where it screws into the carb....fire extinguisher on standby of course...

joe_padavano

Check the rubber hoses that connect the tank to the hard lines and the hard lines to the fuel pump. These lines can deteriorate and crack, resulting in leaks.

rhett838

I think I'm going to start at the carburetor where Yellowstatue suggested, and then work my way back. It sounds like I need the check the tank if the fumes are coming from there or not. From what everyone's saying, the gas tank seems like the source of many problems and requires routine maintenance.

Let me ask this...Is it possible I'm not burning all the gas that's going into the engine? Is the engine just not combusting efficiently, therefore pushing more potent fumes ihrough the exhaust?

I say this b/c my eyes only burn like I said before when I'm backing my car into the garage when the fumes are swirling around my head, and I think that's why my garage smells more like a garage now. Those fumes are just being absorbed into the wall.

Thoughts?

70 cutlass s

If your car wasn't burning the gas efficiently. The signs would be poor gas mileage, loss of power, and gas smell.

After 41 years of service the rubber lines fuel lines are going to be dry rotted. If it was my car I would replace them at the pump and at the gas tank and take a good look at the tank while I had it out. I would also take a good look at the metal fuel lines because they can rust out.

Lady72nRob71

Yes. The unburned fumes are hydrocarbons.
An engine is never 100% efficient and that is one of the reasons companies are putting thousands of $$ worth of electronic and extra mechanical crap on engines now days. The goal is to burn gas more efficiently int he cylinders and use emission controls to take care of the rest.
The bigger the engine displacement, the more hydrocarbon fumes the engine will release. The lack of emission controls on older engines let even more HCs into the air.
I stood behind an idling 1972 455 before in a confined space and the fumes had me running out in about 5 seconds. It was a fine running engine, too - just BIG!
If you are BACKING into a garage, I can see what you are complaining about. Try to park the other way around or install a high velocity vent fan in your garage. I did for fumes and heat expulsion.
If you have to back in, make it fast and shut off the engine pronto. I would probably be pushing it out before starting, as cold starts make the HCs even stronger.

Always keep a running engine out of a confined area, and when you back out of the garage, take note where the wind blows the exhaust.
Murphy's law of campfires states that the smoke always blows towards the tent, which in your case the exhaust will always blow towards the house / garage.
Close garage door to warm the car up if needed.

rhett838

Thanks LnR...I kinda thought that smelling like fumes when you're done driving was part of the allure of owning an old car.

It has the orignal 350 in it, I bet it's not running as efficient as it can. It probably needs to be overhauled...that's on the list. It sucks gas likes it's nobody's business, but like I sad, that's part of owning one of these old cars right?

I need a neighbor like you LnR! An Olds aficionado that can give me pointers about my car...better than any assembly manual! There are some houses for sale near me in the mid-cities if you want to think about moving.

paul879

Dont forget to check the fuel line under the car passenger side front just below in front of passenger door there is a fuel line with a rubber conection about 2-3 inchs long could be a leak ther too line runs under chassis comes out then goes back in to front

rhett838

I took it to my mechanic to get the a/c up to speed, and he said the intake manifold is where the fumes were coming from. Looking at several posts here, it looks like this could be a tricky fix, but I think I'm going to attempt it

He also said I need to replace my oil pressure sensor...where in the heck is that?

And just for fun...I took my back seat out this weekend and found what looked to be the original speakers (jensen) located inside the triangle of death. I have no idea how they got those in there, cuz they were a bizzle to take out!

Lady72nRob71

I would not think the intake manifold gasket would cause the fumes... Is it leaking or is there something else wrong with it?
How did the vent lines look underneath?

In picture below, it is the golden "bell" looking thingie right behind the water pump, to the side. If you have gauges, it will look that. It will have a blue wire attached to it.

If you have the idiot lights, it will look like the temperature switch in the intake behind the above "golden bell".

Did they look the the old ones in this picture?


These old ones are Delcos. However, suppliers could have varied during production. Any pictures of yours?

Glad I can be of assistance... I am usually as close as your computer.
If I move, I want a house in Oregon overlooking the Pacific, but I will settle for a lake in TX country also.

rhett838

That's a great pic! Thanks! I'll put up some pics of the speakers I took out when I get home later. Mine look old, but yours look more original

I have the idiots lights. But there is an aftermarket Oil/Temp/Amp gauge mounted below the dash. Only the oil gauge works, or does it? I thinking of ripping that out though. The wiring is shotty at best. I put in a fuse that lights up the gauge , and the car wouldn't start. However, I wished it worked, b/c I would like to know the temp, esp during our hot summers. But w/o a manual, or knowing which wire goes where, I think it just needs to come out all together.

The mechanic said intake manifold. I thought that was odd, b/c if fumes were coming out of a manifold it would be the exhaust manifold right? I bet it needs to be changed regardless. There are no leaks that I notice.

rhett838

let me add this: When I pull into the garage, I smell gas coming from the engine compartment, but only when I just turn it off. The odor goes away after awhile, but what is that? Leftover gas in the carb?

When I start for the first time after a few days of not running, black liquid shoots out the tailpipe. I looks like water with black soot mixed in. But it only happens when I'm warming it up. Once it's warm, it stops. Is that normal? Should I throw an engine cleaner in the gas tank? Do those even work?

Lady72nRob71

That seems somewhat normal, since you do not have a charcoal can.
If you have an open air cleaner, the smell will be stronger.
Are there any wet or discolored areas around the carb where it could be leaking?

Water vapor is the liquid - very normal.
The choke may be set too rich for so much black soot to accumulate. You could set it leaner and see how it does.
Can't tell you about the engine cleaners... I never had a car run better after using one.

Lady72nRob71

I am not much help on aftermarket gauges as they are all different.
If the wiring is shoddy, starting over would be a good option.
For $429 you can install a rally pac!
The gree wire is for temperature, blue for oil pressure, but those are prolly just hanging on yours now.

I would think exhaust also. You might want a second opinion...

mugzilla

run engine till hot , open air cleaner , if choke is shut/partially shut , it may be your problem...

Also check a couple plugs looking for wetness...

Lalo442

Don't forget to check the gas tank vent lines at the end of the gas tank facing the front of the car on my 69 Convertible S with a 350 there are 2 hard vent lines that go up to some sort of plastic vent and tucks under a brace on the body if that plastic vent comes off it might even leak out of there ...

MDchanic

1. Jensen did not make the original speakers, Delco did.
They look like the ones in the bottom of Rob's picture.
If they say Jensen, they are aftermarket, probably from the late seventies to early nineties.

2. Gasoline evaporates when it is hot, so when you park a car with a hot engine, the gas will evaporate out of the carburetor.
This gas will smell like gas.
On cars from the sixties, the fuel in the float bowl evaporates, rises through the vent tube, diffuses through the air cleaner, and enters your nose. Later cars were equipped with evaporative emission controls to reduce this, because it seems to hurt people in California, though I never knew it to hurt anyone on the East Coast.

3. Older engine exhaust smells gassier than newer engine exhaust. This is partly because older engines are less efficient than newer engines, and partly because catalytic converters both burn excess gas and convert the products of combustion to less noticeable compounds. All engine exhaust used to smell like this in the old days. Being stuck in traffic nowadays smells entirely different than it used to in the sixties. I'm sure our older members will vouch for this.
If you want to smell REAL gassy exhaust, stand behind an old flathead F_rd sometime. The guys who were driving in the fifties will tell you about putting Model T spark coils in the trunk and spark plugs in the tailpipes, so that when they floored it, the unburned gas would light up, making flames shoot out the pipes.

4. The products of perfect combustion are water (vapor) and carbon dioxide (CO2).
Combustion is never perfect inside an internal combustion engine.
The products of imperfect combustion of gasoline include water vapor, CO2, oxides of nitrogen, hydrocarbon chains of varying lengths, and carbon.
You can't see the CO2, the oxides of nitrogen, or the hydrocarbons, but you can see carbon (soot), and you can see water vapor when it cools and condenses into liquid water.
When carbon (soot) and water are expelled from your exhaust pipe, you see black water.

5. To echo others' advice, IF your engine is leaking fuel, common places are the steel fuel line connections and fuel filter connection into the carb., the fuel hoses at the fuel pump and at the tank, the fuel filler neck where it attaches to the tank, the fuel tank top and seams (rust), and the fuel sender seal.
The intake manifold is pretty much the only place I can think of where I would NOT expect to be able to smell a leak, which is another way of saying, "Get a new mechanic."
Because different people's sensitivity or lack of sensitivity to gas fumes varies so much, I would recommend finding someone who is familiar with these cars to give the ol' crate a sniff. The fuel you smell may be completely normal, or it may be the sign of a howling leak. Until they invent smellivision, we can't help you with that one.

Good luck.

- Eric

Bluevista

This thread is over a year old guys.

JamesPDX

So? The information is still valid to many members.
Thanks Eric, and others for your contributions.
James

ragtop71

I love this site< My convertable started smelling like gas to and I had multiple issues 1. gass was leaking around cap when I had it filled it would spill alittle when hitting throttle and 2 the gas was spilling alittle from the filter screw on the front of the carb. but hearing from all of your guys advice I am going to look at tank and vent lines ect. thanks C/O

JamesPDX

Great to hear from you. You have a nice looking ride.

Yes, this is a very good site filled with knowledgeable individuals who are willing to share their experience and lessons.

Please let us know what you find.

Don (MDchanis) forgot to include carbon monoxide (CO) in his comments about gas engine combustion byproducts above.

serta1

Is there a way to test these to make sure they work properly? I can get air to travel from the center line to the vent going to the charcoal cannister but not from the two outside lines. Thank you.

Tedd Thompson

If your car starts slowly (cranks a lot) you maybe having leak down from the lead seals in the carburetor bowels allowing gas to escape into the intake manifold. This occurrence will cause a gas smell coming from the manifold and it can be intense... Just a thought to add to what has already been suggested....Tedd

Octania

Plus four now...

still a valid thread

So, that silvery can in the back seat area shown above- is that a charcoal can or just a house for venting tubes?

serta1

Thank you for the response. I am in the process of installing a new fuel tank. I do not have any fumes / odor yet. I am trying to make sure that this thing is working OK before I install the new tank. I blew out all the lines running from the charcoal cannister and fuel pump to the rear of the car and the line from the center of the separator to the line going to the cannister. Just noted that I could not get air to go from the two outside lines. This is a 71 Olds Cutlass that I am working on. Thank you.

MDchanic

It's called the standpipe, Chris. Its operation is actually very well illustrated and described in the CSM (Emissions section, if I recall).

The trick to finding the reference is to know what they called it.

- Eric

serta1

In my 71 Cutlass the charcoal cannister is located in the engine compartment up by the radiator on the passenger side. The unit behind the rear seat is supposed to separate the fumes from the fuel. The center line coming out of the separator is supposed to send fuel overflow back to the tank. Not sure about the other two, still trying to understand how the rest works.

serta1

I am not sure where the CSM is (I am 30 years Army retired, CSM stood for something else). Is there a part number for this item? If mine is not working properly I will have to find another one. Thank you.

MDchanic

No, this is not a question to bother the Command Sergeant Major with.

CSM: Chassis Service Manual. If you don't have one, you should get a real, original, paper one.
They're available on eBay, and usually if you watch, you can get one for a decent price.
You can download scanned copies of that and many other things for the price of a one-year membership in the Automotive History Preservation Society at WildAboutCars.com.

- Eric

serta1

Found the number for the Standpipe.

Group 3120, 407742

Cannot find anyone that has any for sale and waiting for the CSM.