Another gas smell thread

[Honolulu]

Like many, I smell gasoline when and where I hadn't oughta. I'm pretty sure the tank and evaporative system in the trunk are in good shape, after removing the tank with a gallon or so, holding it up and looking for drips in various positions.

I suspect warped carb castings, and lacking the drain tubes, the smell is coming in through the vent system in the gutter, forward of the windshield.

So.... having seen warped carb castings on a spare set of Zenith carbs pulled from a 2800... has anyone tried to rectify this by using two gaskets between the castings, rather than the usual one? What success or comments?

I'd rather not remove the carbs and play with them. I've done that and though I'm not at all reluctant to synchronize them again, the rear carb is a hassle to take off and at least as much of a b()tch to put back on.

 

[AndyM]

I'd do some more investigation in the trunk before pulling the carbs. The tanks like to leak at the pinch weld seam, but it sounds like you have already ruled that out along with the evap stuff. You should also check the seal on the sender and the gas cap seal. The negative pressure in the trunk - especially with the windows open - draws the fumes in. A new gas cap solved my gas smell.

I'm not a carb guy, but it the warpage isn't too bad on the carbs, you may be able to dress them using emery paper on a flat glass surface. I did this with each of the runners on my D-Jet since they had all warped from being over-tightened over the years. That, along with some good (not silicone!) gasket dressing and they seal great. Double gaskets may work too, but I'd see how bad they are warped first.

 

[Honolulu]

Yeh...

thanks for those notes, Andy, but I have done all that and more, having had this car for 15-plus years, and 14 different 2002s, a 2800CS, 2500 sedan, Bav, etc., etc., etc.

BTW it's the relatively lower pressure in the cabin (not the trunk as stated) that draws fumes from the trunk into the cabin. I think if the gas cap were the culprit, the seal around the filler neck would block fumes from the filler neck, which would also have some chance to leak out between the filler tube cover and the body gasket.

However, the one thing I haven't done yet is positively seal off all airflow between the cabin and trunk. 'Spose I gotta get a can of that spray-foam stuff and crawl into the trunk.

 

[AndyM]

Yeah, I kinda figured you had already checked all of that, but you never know. Don't discount the gas cap, though. I didn't believe it either, but it worked.

And, yes, you are correct on the cabin low pressure with the windows open -- what I typed doesn't make sense since my trunk doesn't have windows. :wink:

Let us know what you figure out.

 

[velocewest]

I haven't tried the multiple gasket routine, but I've used a block of wood and sandpaper to true the carb castings. That was successful.

 

[Malc]

Breather pipe from the fuel filler pipe that exits in the boot (trunk) floor present and clear?
(or are you suffering from DOT emmisions stuff?)

Check the lines under the car and around the fuel pump, a very slight leak can cause the smell of petrol to enter the car
Malc

 

[Honolulu]

BTDT

Thanks Malc, the little tube from the filler pipe goes to the canister above the right wheel arch, then a blue plastic vapor line goes forward to the engine compartment.

Yup, I know how these things are SUPPOSED to work, and I could write the FAQ as well as anyone about the 15 dozen ways they fail and what to check. But now the doctor must cure himself.

Last thing, I guess, is to climb into the trunk, have the friendly daughter shut the lid, and see if the trunk lid seal is still sealing. Shortly thereafter they come into their inheritance... and can send the old heap off to the crusher with/without yers truly in it. Jimmy Hoffa here I come!

 

[glenn in encinitas]

Honolulu-

I had a similar experience and it was the O-ring around the sending unit for the fuel gauge. It's cheap and an easy fix if it's the culprit- assuming you haven't already checked it.

Good luck,

Glenn in Encinitas

 

[HB Chris]

When I checked my vent lines they weren't hooked up to the charcoal canister under the battery nor to the manifold/carbs. Without a vacuum the gas will stay in the trunk reservoir and smell. At least that's my theory. And my car no longer smells!

 

[baldo]

I also smell gas in the trunk which then gets sucked into cabin with windows down. I have changed fuel lines and both o rings. I have taken tank out and had it tested for leaks, none were detected. I have a 75 csi, so the vent hose on the filler neck goes out the trunk floor behind bumper and that all seems fine. After all this there is still the gas smell in trunk. I believe there are 2 gas caps for our cars, one vented and one not. Which is the right one for a csi? Mine says O.L inside.
Is it possible to seal off trunk from cabin? Any help would be appreciated.
Charlie 75csi

 

[Malc]

I Snip..... I have taken tank out and had it tested for leaks, none were detected. I have a 75 csi, so the vent hose on the filler neck goes out the trunk floor behind bumper and that all seems fine. After all this there is still the gas smell in trunk. I believe there are 2 gas caps for our cars, one vented and one not. Which is the right one for a csi? Mine says O.L inside.
Is it possible to seal off trunk from cabin? Any help would be appreciated.
Charlie 75csi

The rubber "neck" ok, not spit or perished?
Breather tube exiting the neck clear, not kinked etc
steel lines from the pump and the FI return ok, no pin hole leaks?

You can use either cap as the vent tube that exits the trunk is supposed to act as the "breather"

Yes you can seal the trunk off, take the back seats out and you should see the rear wall. Use seamsealer and that expanding foam insulation stuff that comes in a can - know the stuff I mean? - for up between the wheel wells and the outer panels.
malc

 

[baldo]

Thanks Malc,
I will try and seal off the trunk from the cabin and see what happens. Unfortunately somebody cut speakers into the back shelf so those are 2 big holes to seal along with all the others. Fuel pump and metal lines seem to be ok.
Hope your project is moving forward so to speak,
Charlie

 

[HB Chris]

Cap

OL refers to "ohne liechtung" or something like that, which means without venting. Older MBs did the same thing, some used with and some used without. Charles, since you have the rubber cover including the plugs that access the screws, maybe you should try a vented cap. That would give the gas more opportunities to vent outside the car, just a thought.

 

[baldo]

Chris, I'll see what sealing off does and also look into gas caps. Hows your car coming?
Charlie

 

[Honolulu]

"OL" stands for Ohne Luftung

"OL" stands for Ohne Luftung and yes it means without venting. Not certain which is correct, but it seems that the tank should breathe through the vapor hose. I had a 2002 once that starved for gas this way, opened the cap and all was well. Forget what I did to cause or cure it otherwise, think it had something to do with the vent line (did I plug it or wot?)

Since this thread is still alive, I'll summarize the ways I know/remember that our carbed cars let a gas smell into the passenger compartment, with the owner action and fix. CSi will be largely similar.

In the back....
* Leaky tank (some say cracks may be invisible (?) but take it out and test, epoxy seal, or weld)
* Leak/crack in filler neck (inspect and repair/replace)
* Leak/crack in vapor line from filler neck to vapor can above right wheel arch (inspect/replace as necessary)
* Leak/crack in vapor can above right wheel arch (inspect/replace as necessary)
* Leak/crack in vapor line vapor can above right wheel arch running forward to charcoal can under battery (inspect/replace as necessary)
* Bad o-ring on sender (fill tank full, remove right side trunk floorboard, rock car and look for leak)
* Bad/missing 1/2" long plastic cylindrical seal on metal output line from sender where the flex hose connects (often lost when flex line is changed, flex hose may not seal without)
* Bad flex line from/at sender (inspect, replace)
* Bad trunk seal (climb in trunk, have trusted assistant close trunk, look for daylight around seal, CNPR has new seal, not cheap)
* Body panel behind rear seats is NOT airtight (seal with foam spray can)

And up front....
* Leaky carbs usually show a stain (inspect, remove and attempt to sand castings flat or double gasket)
* Missing seal across front edge of "gutter"containing window motor, allowing fume to enter fresh air system (repair/replace)
* Missing one or all three tubular water drains from gutter allow engine compartment fumes to enter fresh air system (replace, CNPR)
* Vapor line not connected to charcoal can, or can missing entirely (connect vapor line to air filter box)
* Leaky flex lines to/from fuel pump (replace periodically, or else)
* Leak at joint between flex fuel lines and hard lines (flex lines usually fail at their ends due to flex stresses, inspect and replace)

A few of us will be able to add to this list, which should turn into a FAQ, illustrated and keyed. I've been to all these locations and each of them may contribute to the perceived smell, often several little leaks will be present.

Charlie

 

[baldo]

Charlie,
Thanks for the clarification on the gas cap. I removed my tail lights and noticed I'm missing the gasket on the left lense frame. The right frame gasket was a little loose in the corner also. This will allow air into trunk. (another thing to add to the list of potential suspects)
I will try and track down the gaskets or maybe try and make them and see what that does.
Charlie

 

[pmansson]

gas fumes in the car on twisty roads

I get a very noticeable gas smell in the car, with windows closed, but only when going on serpentine roads....
No smell on more normal roads !
What might be the cause?

 

[CookeD]

Gas smell, cont'd...

Hey All,

Replacing all my flex lines, including the from the tank sending unit to metal fuel line, and noticed that the 1/2" whitish-plastic shim that goes into the flex line has a longitudinal crack running the entire length from front to back.

Can I get just that shim, or do I have to buy an entire line?

Thanks in advance!