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Gas fumes when the windows are open...


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Hello all,

 

I have searched this forum up and down and have had some luck getting the fuel smell down a bit, but It still remains! When the windows are closed, there is NO smell of gas. I shoved some of those tree fresheners to verify that the smell was indeed coming from the trunk. I am getting the venturi effect in the car when driving down the road with the window ever so cracked. So..... I replaced the fuel sender o-ring (used silicone lube to make sure it was in there good) and the gasket by the filler neck. Upon inspection, I had found that the fuel sender never had the plastic bushing which is where some of the fumes are coming from. I also took the filler neck out and saw absolutely no cracks or anything, yet a gas smell is still coming from there. I noticed that the orange gasket that seats to the fuel cap was rotted/destroyed so I made a gasket from this rubber material from Lowes(I had seen someone who did this on this forum and it solved their problem, but I probably did it wrong - I will order a proper gasket because i still get a strong smell from there). I also have no idea where the vent line from the filler neck goes. If I have read correctly, it says that theres a rubber grommet that goes to the outside on the bottom of the trunk? I can't seem to find it. Does it go to the plastic canister that hangs from the top of the trunk? There is an open vent line that is just coming from...well I have no idea. Any help would be appreciated. Thanks!

Edited by cree02
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Early cars vented by a hole in the center of the trunk IIRC. US cars your vent goes to the vapor recovery tank and from there to the firewall and to um, your air cleaner. Check your plastic elbows in the trunk to make sure they are tight, thereby venting the cabin, and not sucking fumes into the cabin when you open the windows.

 

74 and later cars had a charcoal canister. If yours does then the line goes to that, then to the air filter.

 

Been a long time since I worked on carburetor car........

Try that.

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The vent from the tank under the rear window should be routed to the front of the car in a blue plastic line that comes from the fire wall through the same grommet as the clear/whitish fuel supply line. It is also possible that the vent tank has cracks or the fuel tank itself has some rust pin holes in it. if you don't have the fuel pressure valve anymore the return line should be plugged at the tank. 

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1 hour ago, cree02 said:

I can't seem to find it. Does it go to the plastic canister that hangs from the top of the trunk?

Yes its supposed to go there, its kinda like a vapor storage tank.

Line from it goes forward to the engine compartment, if fwd line is loose/damaged at that tank you can definitely get fumes being sucked into the passenger compartment.

You can repair as required or just route the line overboard like earlier cars did. Check your Fuel filler elbow for damage as well.

Another possibility is your gas tank is rusty along the mounting flange and fuel vapor is escaping there.

Thats fairly common actually. The factory foam seal between the tank and car seems to hold moisture there.

Edited by tech71
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The gas cap should provide a good seal. The tank is vented through the plastic tubing in the rubber sleeve from the tank to the filler cap. The tubing goes to the vapor canister under the rear shelf in the trunk. From there, it goes through the cabin to the engine compartment (near brake booster on driver's side), and connects to the charcoal canister. A braided rubber hose connects the charcoal canister to the air cleaner and the manifold vacuum connection under the carb.

My crude sketch shows the routing.  Check all  hoses and connections for leaks.

Hope this helps...

John

 

Fuel System.jpg

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The flexible rubber hose that connects the fuel pickup nipple with the clear plastic fuel line that begins near the right wheel well:  if that's the original, cloth-covered hose, replace with new all-rubber fuel line from your local auto parts store.  That old cloth-covered line is OEM and will crack beneath the cloth cover so you won't notice.  It'll then ooze gas, which wets the cloth and evaporates, giving a nice gas smell in the trunk.  Be sure to (1) clamp the new hose at both ends, and (2) don't forget the little plastic sleeve at the fuel pickup nipple.

 

ADDITION:  Be sure and plug any holes between trunk and passenger compartment.  If a PO (you'd never do this, I'm sure) cut holes in the package shelf for speakers, cover 'em with something airtight and relocate the speakers,  And look way up in the upper corners of the trunk's forward panel (bulkhead) that separates trunk from pax compartment.  There's usually a small passageway for wiring, hoses etc up there that was plugged by little chunks of foam stuffed in during manufacture.   That was 45+ years ago, so make sure those holes are still plugged up.  Very little gas vapor can make a big smell, so make sure the bulkhead is nice and tightly sealed.

 

mike

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