Every summer I get a horrible gas smell that sometime permeates throughout the cabin of my 1993 240. I have noticed that after driving the vehicle and parking that there is hissing coming from the gas cap which is relieved when I take it off. No visible leaks detected. Gas cap has already been replaced

Any help would be appreciated.
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1993 240, 1992 240GL, 1985 240DL Wagon, 1983 240DL

Yet first, today, we have (what I believe to be) a clogged valve on the EVAP charcoal cannister on the 1990 240 li'l red DL wagon beastie. At the front left fender. I pulled the EVAP line from the gas tank filler neck on the other two 240s, and they are equally difficult to blow through. The on-cannister check valve may be faulty, or the entire cannister is guck inside. Gas vapor ejects though the gas cap. No wonder, the gas smell. No leaks thankfully at the sender and adjacent spaces.

Synchronicity again. Via your brickboard.com.

The vapor line coming off the top of the gas tank filler neck just inside the trunk or wagon cargo area connects all the way to the EVAP charcoal cannister.

These the vapor line itself can become pinched.

The check valve inside can get stuck or act slowly to positive pressure inside the fuel tank and also to engine vacuum that draws the vapor into the air intake right on the throttle body.

Yet we see we can't purchase these new anymore. In the following turbobricks article, i recall cleaning a charcoal cannister EVAP valve in 140/160 like decacdes ago, when you could.

http://forums.turbobricks.com/showthread.php?t=284229

Happy Sundae.

Relocation' MacDuff (Spokane WA and Coeur d'Alene ID: EVIL, EVIL, EVIL.)
--
The Volvo 164: The Mightiest of All Volvo Automobiles in Perpetuity

Ooooooph, we gots some images.

SO, the Stantz brand locking gas cap does not seal. Or someone broke it trying to remove it to siphon my gas from my Volvo 240 gas tank. Or it wore out. I dunno. It does not seal. Should I get another WA-state emission test, they test the gas cap for pressure seal in both directions.

In warm and hot weather, and with your gas in your gas tank sloshing about, gas evaporates quickly building pressure. Such pressure pushes the evaporated gasoline through the EVAP vapor line (like PCV vacuum line) hoses and into the EVAP canister, as the activated charcoal 'holds' onto the fuel. On engine start and with accelerator action, the two vac lines between the Volvo 240 throttle body take action. One vacuum line controls the check valve, the other vac line draws vapor into the engine. I'm not bothering to figure out the action more deeply right now.

Mostly the gas odor is the non-sealing gas cap. No fuel leaks whatsoever anywheres.

When you stop, and all things fuel tank cool down, a vacuum can form in the tank, drawing air back through the though the EVAP. I think through the large drain hole at the bottom as it appears to have some kind of plenum that open on vacuum through the vapor line between the fuel tank and the EVAP canister.

The EVAP canister, removed from under the left front fender, in front of the tire. One zip tie strap was broken. Not very safe had the other broken!!!!



There seems to be a vent function in the gas cap, yet from how much pressure (PSI or BAR?) is way, way higher than the pressure build from the quickly evaporating and expanding gases pushing through the vapor line at the top of the filler neck on the run under the Volvo, into the engine compartment, and a left turn to the Rochester (GM) brand EVAP activated-charcoal under the fender in front of the tire.

I found one of the two zip tie straps that secures this poor EVAP canister broken, so I have the (black is better) plastic zip tie straps thingies to re-secure the EVAP canister.

1990 Volvo 240 EVAP Canister Made by Rochester - Check Valve & Vac / Vapor Line Connect Detail - Vacuum Controlled Check Valve at left in Image.



The vacuum lines from the throttle body connect to the check valve. The single larger line is the vapor line from the top of the fuel tank. The fitting at far right is capped, unless you have a carb on a 240. (I'd like a carb on a 240.)

The check valve was stuck. Tried a vacuum line section to blow and draw on either check valve line connection. I dunno what line is what. I guess the top vac vapor line connection is for vacuum control of the check valve. The bottom section is to draw vapor through on running engine air intake vacuum.

Though the gas tank pressure can be rather high.

Use some brake parts cleaner in the each of the two holes. Connect a 8 foot section of PCV-rated vapor vac line, and blow and draw.



I can't find my vacuum gauge to see how much vac it need to operate. Yet it does actuate.

I've done this on 140s/160s, and you could remove the check valve to clean it. So, barring a 70$+ replacement. I'll try this. I'm letting the brake parts cleaner evaporate, so I can see that is actuates when there no brake parts cleaner acting as lube, with the displaced hydrocarbons in and around the valve.

The canister is light, meaning the activated charcoal is dry and is not filled up with gunk. At that point, you may have to replace it.

The thing is heavily coated in undercoat. This poor 1990 240 DL wagon has all smashed in front in like 1999 and 2000. All replaced fenders and hood. yet some years ago the body work was not adequate, and I added fasteners that should have been there to secure the sheet metal assembly.

Going to put it back together. A new locking gas cap. Should be good to go!

And two other 240 to do this to, also.



BrickPix image #12245 is of a Volvo 245. Heh.

Questions?

Wacky, Wacky, Wacky-Toe-backy, Wackington State. Idaho is no better.

Use to be the fiscal libertarian state. No income tax. Yet it is a welfare heck hole and massively corrupt, massively entitled, unlike what you read on teh i-net, so says my first-hand encounters here in the last nine years.

Hope that helps.

MacDuff.
--
The Volvo 164: The Mightiest of All Volvo Automobiles in Perpetuity

On the subject of the fore mentioned vent hose of the filler necks rubber catch cup.

As I remember the gas cap vents or let's air in from under its own rim and into the rubber cup. Some may think it's there only for spillage from the filling nozzle.

Make sure the hose is routed down some bracing for the right rear fender under a couple clips.
Putting things down in the lower cubby hole can pull on the hose.

The end of the hose should exit at the bottom of the wheel well. There is a rubber plug there that the hose has to fit into in order for it to drip outside of the car and onto the ground.

After few drops or the fumes from this they end up into the trunk area. That stuff whips right up into the cabin as it permeates forward through the back seat of cardboard and foam.



The point about checking the tank piping for rust was very interesting.

I have never dropped a tank before or seen one in a junkyard dropped. Mainly because they usually have a big hole punch into the bottom to prove its emptied.
Nobody really wants to pull a bad tank when the sender is reached from the top!

You shouldn't hear that noise very often except in the summer or after the tank has been agitated from driving. A low fuel tank can slosh a lot more and the fuel will change temperatures quickly.

There is another hose that goes up from the gas tank to a vapor canister located under the front bumper, drivers side.
I do not know where the attachment point is on the fuel tank. Maybe it's another relief valve or on the roll over valve on top somewhere?

You want to the check those hoses in the engine compartment coming from the canister to the throttle area. There is a check valve on the canister that get activated by throttle vacuum at idle or de-acceleration. Any high vacuum event, as I remember?

When it's activated gas fumes are drawn from the fuel tank.
You have to pull vacuum on one hose and blow in on inlet side of the check valve that's from the canister to verify its operational status.


A disclaimer! I have never done this test below!

I can imagine a person could add air into the gas tank hose at the canister side back to the tank to verify its integrity.

The line should hold a small amount of pressurize within the line itself or inside the gas tank as a whole unit?

I guess if one pumped enough in and if you had someone at the rear you might hear a relief valve or cap vent outwardly.

I have a very handy Silver Line Model of the Mity-Vac. It's a hand operated pump for testing cooling systems and vacuum controls. Great for pressurizing a cold engine cooling system looking for water leaks anywhere!

The Silver "name" is for pot metal body of the pump! Whoo-hoo!

Also, You might want the gas tank near full, otherwise, it would be a lot of hand pumping, even for a guy! (:-)

Checking these two locations, as suggested by posters, should elimate the problem.

Good luck
Phil

Check the condition of the vent hose that runs off the gas filler neck (if I recall the location correctly). Could be unplugged or cracked allowing fumes out.

Also, check condition of the filler neck and gas tank. This is unlikely in NM, but tank could be rusted at top allowing fumes out but no visible leak. Make sure filler neck is properly attached.

Just thought of one other thing to check. When accessing the top of the tank, check the metal fuel pipes for rust. Look at where they attach to the fuel sender. Some years ago, I had to replace the fuel sending unit on my 240 because the the fuel pipes were so badly rusted.