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1975 Eldorado Convertible - Gas Smell

Started by djrobnyc, September 18, 2012, 12:05:18 AM

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djrobnyc

Hi. I have a 75 Eldorado that seems to be running well. However, after I shut the car off, there is a pretty strong gas smell that lingers -- I have to leave the garage door open for at least an hour to air out the smell.

I can't say for certain this smell isn't happening while I drive the car; but I do not notice anything while driving. The only thing I do seem to notice while driving (in Park or at a stoplight) is a pretty good amount of heat radiating from underneath the car -- as far as the doors.

I understand there may be some lingering fuel in the float bowl after shutting off the car  - but would this produce such a strong "raw fuel" smell?

I do not notice any visible gas leaks. And the car is getting 10 miles per gallon - so I don't appear to be "dumping" any fuel. Any direction as to what to check out would be appreciated. Thank you.

Rob Melstein

TJ Hopland

10 mpg?  Thats lower than I have got with any of mine.  13-15 has been typical on my 73.  My 75 gets close to 20 for some reason. 

Can you narrow down the area the smell is the strongest?    Ever try to remove the gas cap immediately after a drive?  Just wondering if you will notice a woosh air sound indicating that the tank is either under vacuum or pressure.

Does this seem worse on hotter days?   How quickly does it start and is it different cold vs hot engine?  cold vs hot ambient?

One area that often gets overlooked is the hoses back by the gas tank.   They are only about a foot long each.  The connect the steel lines that come off the sending unit in the tank to the steel lines that run along the frame.  They are above the rear axle and you can replace them without dropping the tank.  There are 3 lines.  1/4 return, 5/16 vent, 3/8 fuel. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

djrobnyc

#2
Hi and thanks for your response.

I thought 10 -- combo of some parkway and local driving - was decent. I have not removed the gas cap immediately after a drive - I will try that.

As for some more details:
The smell seems to be the strongest coming from about the front wheel wells area through the front door. Some heat coming off there too.

As for cold vs. hot days, maybe it's worse on hotter days but I can't say for sure.  Regarding starting - do you mean how soon does the smell start or how does the car start? The car usually starts with 1-2 kicks - cranking 15 seconds or so. The smell usually only starts when the engine is warm.

Sorry - I'm kind of a novice when it comes to repairs, but if you have any further advice on what I could have a mechanic check that would be appreciated.

Rob Melstein

Davidinhartford

If the smell is coming from the front of the car  I'd check the fuel line up front.   Then the fuel pump, then the carb base gasket.  In that order. 

My 74 Calais sedan had that smell when I bought it.  The  carb gasket was bad so it leaked pretty good.

"Cadillac Kid" Greg Surfas 15364

I "chased" a gas smell on my '75 Coupe for quite a while with no luck.  Changed gas cap, fuel line hoses, emission lines, all with no change in the gas smell.  It seemed to appear (smell) after I drove the car and after the car sat for a while, was gone.
One day I parked the car on a slight down hill with the front end lower and found a growing puddle of gasoline under the car.  When I parked level it did not leak, but when parked with the nose lower, leaked every time.
I seems that the seam of the fuel pump was leaking and apparently had always been the source of the gasoline to generate the smell.
Changed Fuel pump. Smell (and of course leak) gone.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

TJ Hopland

Yes my starting questions were not how long it took to notice the smell but how long it takes to start the engine under various conditions.  You say it typically takes 2 15 second cranks?  And that is hot or cold engine, hot or cold ambient, sitting overnight vs say a full week?   Im just trying to figure out if there are signs of excessive heat and vapor lock or heat soak issues.   2 15 second cranking cycles is not great under some conditions but is not as bad as I would expect if there was if there was some serious heat issues. 

And from what you can tell the smell is always there now just is maybe a little stronger on a hot day?

Do you think its still there if its parked outside? 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Guidematic


OPne thing to check is the heat riser valve. There is a thermo vacuum switch that controls the engagement of the valve. It applies vacuum to the valve when the engine is cold to redirect exhaust gases through the heat riser passage under the carb. Once the engine warms, vacumm is cut allowing the exhaust to pass normally through the outlet of the manifold.

The TM switch can malfunction and not allow the valve to open when the engine is warm. This allows for excessive heat at the carb base which can boil off the fuel in the carb after shut off, giving a strong fuel smell.

After much searching to find the problem with the '75 CDV I had (which the main part was a high coolant temp) I found that this to be the problem. I just merely disconnected the vacuum supply, and the problem was eliminated.

Mike
1970 Fleetwood Brougham 68169
1985 Eldorado Coupe 6EL57
1988 Eldorado Biarritz 6EL57
1990 Brougham d'Elegance 6DW69
1994 Fleetwood Brougham 6DW69

76eldo

There's a leak somewhere.

I would check for obvious things like the fuel line at the fuel pump, the pump itself, but depending on the condition of the steel lines running under the car, you could have some rust and pin holes that allow the gas to seep out, hence the need to crank it a lot on initial startup.

The rubber hoses at the tank outlet, if original, may be brittle and cracked and allowing seeping.

You will need to get the car on a lift to properly inspect all of this, and gas fumes can be really dangerous in a closed garage.

brian
Brian Rachlin
Huntingdon Valley, Pa
I prefer email's not PM's rachlin@comcast.net

1960 62 Series Conv with Factory Tri Power
1970 DeVille Conv
1970 Eldo
1970 Caribu (?) "The Cadmino"
1973 Eldorado Conv Pace Car
1976 Eldorado Conv
1980 Eldorado H & E Conv
1993 Allante with Hardtop (X2)
2008 DTS
2012 CTS Coupe
2017 XT
1956 Thunderbird
1966 Olds Toronado

djrobnyc

#8
Thanks everyone for your help. I do realize this is something that's need to be taken care of ASAP as we're talking about gas here.

Some of you have asked for additional information to help diagnose the problem. What I also can tell you is that I use the car about once a week -- during good weather of course. So if I were to use it next weekend, there would be no gas smell before I would start the car. I only smell the gas after driving it as I'm putting the car into the garage (takes a few minutes to do so without bumping into anything!) and then shut the car off.

I do not really notice the smell when driving - I don't notice anything from the driver's seat with the top down - but that's not to say the smell isn't there, right? It could just be dispersed in the wind...

As for starting the car up, when it's cold, I usually pump the gas 1-2 times and crank 15 seconds or so. If it doesn't start then -- maybe 50% of the time--  I get off the crank... and then turn it again a couple of seconds later. It always then starts within 5 seconds of the second cranking.

For the first time since I've gotten the car - last May -- I did leave it outside overnight. It may have gotten down to 50 degrees or so temperature wise. When I went to start it the next morning, it would not turn over on the first or second time.
Had to go for a third.

I will bring the car to my mechanic this weekend to check this stuff out - but is there anything specific to the Eldo that he should look for? Or is this pretty standard mechanic stuff?

Thanks for everyone's help.

Rob Melstein

Guidematic


The fact that you have to keep cranking the car tells me that there is no fuel available for the first few seconds of cranking.

It is possible that the fuel bown in the carb is draining down. Personally I have not seen it, but Quadra-Jet carbs have plugs in the bottom of the fuel bowl that can leak. They can drain out over several days, or overnight. That can cause the fuel smell and the long cranking.

I would still check what I mentioned previous, it's a quick check.

Also look for any external leaks when on the hoist, or signs of a leak. Generally, leaking gas will leave a tell tail stain after it has dried.

Mike
1970 Fleetwood Brougham 68169
1985 Eldorado Coupe 6EL57
1988 Eldorado Biarritz 6EL57
1990 Brougham d'Elegance 6DW69
1994 Fleetwood Brougham 6DW69

TJ Hopland

A 75 would have had a cat converter.   If its still got one and its partially plugged up that would explain poor mpg and excessive heat in the engine. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

djrobnyc

#11
Would that also explain the "gas" smell?

Rob Melstein

TJ Hopland

Anything that causes excessive heat in the engine will make gas evaporate quicker and its the evaporating gas that you are smelling.

Sometimes the cat can create odd smells when it or the engine has problems but usually its more of a rotten egg sulfur like smell and it goes a way pretty quickly after you shut down.   
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Scot Minesinger

Do you know the history of the car?  Someone had replaced my fuel lines with three sections and splices.  The splices all leaked.  Could not get those compression fittings to not seep.  So I replaced them with the one piece sections from a company that made pre-bent full length sections.  Takes a little while to remove the old clips and puzzle the new lines in.  You need to go through the fuel delivery system from gas tank cap, gas tank, rubber lines, metal lines, rubber lines to pump, fuel pump and metal line to carb plus carb.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

TJ Hopland

Ya compression fittings only work when used with the proper type of line.   

Most people replace fuel line with brake line which is too hard for compression fittings. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

robpp

#15
2 things seemed to contain gas smeels after I bought my 76 Eldorado......


one was an air filter, it was missing,   :'(


the other was the simple gasket on the top of the carb under the air cleaner.

last idea:  my gas cap would not hold a vacuum as the rubber was shot.

with all these things fixed I hardly smell fuel in the garage now.




gas mileage:  I get 10 MPH with about a 50/50 mix city/hgwy. if all highway I get closer to 13.

one thing to remember in the differences from the earlier ones were these last few years were heavily DETUNED. my 500 CI 76 is rated at 195 HP. 8.5 -1 Compression. plus we had all sorts of EGR and other gimmicks to lower fuel mileage.

Rob Powe
CLC 27372
1976 6EL67 Chesterfield Brown/Buckskin