I pulled my gastank down to replace the sending unit and found 2 lines comming out from the top corner of the tank that looked like they were once connected to something but now they are just laying there venting fumes into the atmosphere which explains why I always had a heavy smell of gas fumes whenever I got through driving my car. Is there a simple solution to fix this, or any suggestion that would work since there doesn't seem to be anyone who sells those charcoal canisters that they use to vent the lines.

 

I'd run a rubber hose and clamps between the two, until someone comes up with an answer - you've gas evaporating, certainly not helping your gas mileage or anything else!

 

Don't be so quick to cap those off. One or both could serve as a vent line as well. My '67 Delta has two of them coming off the top right front corner. They're rubber hoses, about two feet long each, and they extend up under the body and attach to little clips. Yes, some gasoline will evaporate through them, but if you cap them off, air won't be able to get into the tank as fuel is drawn out, and that can ultimately prevent fuel from being drawn out or possibly even cause the gas tank to collapse.

Frankly, the amount of gas evaporating should not be enough to be noticed. I never smell it after driving my car. You should make sure you don't have a leak somewhere else, and you should make sure these lines, if either or both also serve as vent lines, are properly routed. As I said, on my car, they are meant to be routed upward above the tank. If their ends are level with or below the tank, fuel could be drawn out through them, and that's what you could be smelling.

 

I'm not 100% sure but I don't think the 68's had Charcoal canisters on them to absorb the gas vent smell. That design came later.

Those two hoses should be different sizes, and should be connected to a small plastic gas tank vent surge tank. This very small tank is then tucked under a tab that sticks out under the car body just above the rear axle. It's mounted vertically so any gas that tries to escape ends up draining down the other tube. In theory, keeps gas off the ground and more importantly off your garage floor.

I've attached a surge tank auction from Ebay (below) that should work for your car.

http://www.ebay.com/itm/68-69-70-cut...60dbbe&vxp=mtr

 

esisson nailed it. The two lines are for the small plastic fuel vent surge tank. My 1969 Cutlass had the lines blocked off when I bought it, but I later replaced with the proper tank similar to that listed in the ebay auction in the prior post.

Two bits of advice: 1) use the most flexible fuel line you can find to avoid kinks when you mount the surge tank and (2) you may want to slightly reroute the mounting location . I simply flipped the mounting bracket 180 degrees because otherwise the surge tank was directly above my aftermarket exhaust. I did not think it wise to have the potential for gas to drip onto the exhaust.

 

The Parts Place sells the correct vent valve.It's part # FT2637T.

 

Fusicks part number- GTF690K

 

Pic below showing the typical "surge tank" set up...two rubber hoses run up to the plastic "tank" (it's a white plastic but discolors over the years from gas fumes). The whole assembly is held up against the floorpan underside with a clamp so that the sure tank is VERTICALLY ORIENTED.

The pic shows a setup from a '70 car. Check an Assembly Manual to see if your '68 used a similar setup.

 

'68 didn't have that "surge" piece in there. That started in '69.

Those two hoses are definitely vent hoses. My originals had a sort of spongy substance in the top end of one of the outboard hose - what they call a "restrictor" in manual section 8, page 111, of the '68 assembly manual. The inboard hose had nothing in it. They lead up from the gas tank and then are retained against the body by a clip that's there. I was able to reuse my originals. I don't get a gas fume smell but I did at first just after restoration. The problem was the large "O" ring gasket around the sending unit in the tank - it didn't seat right so I had to take down the tank, re-set everything and put it back. Haven't had a problem since then.

Randy C.

 

The 68 442 Convertible we're working on has the plastic valve. The clip that's mounted fits the valve perfectly. I looked @ the assembly manual and I see what you're talking about. One thing I have found with the assembly manuals is,they are not the be all end all. The problem with assembly manuals is,they were never meant to be in the possession of anyone outside of the plant. There were revisions made and sometimes the revision made it's way into the manual,sometimes they didn't. If you look @ the last revision on that page,it was 3-12-68,basically 4 months before the end of the model run. So it's possible a change was made to the 69 style vent system but it didn't make it into the 68 manual. I'm not saying I'm right and you're wrong,just the opposite because I learned a long time ago never say never.

 

I agree with what you say about assembly manuals. However, here are a few dates to consider in the thought process:

My car was built in the first week of April 1968 (probably about April 5th based on dated original parts to the car) and it never had the fuel vent surge tank. The vent hoses were as described in the '68 assembly manual. It's a Lansing car and has been in my family since it was new.

The '69 assembly manual does show the "surge tank" piece that's pictured in the entry by 70Post (also on page 111, manual section 8 of the '69 assembly manual). There are changes on that page that range from 3-12-68 thru 1-20-69.

I believe it is possible that a change may have occurred with the '68 model late in the production year (April, May, June or July) but the change was definitely in effect for the '69 model year.

Is it possible the surge tank was added to your car in later years, or that the gas tank was changed out and a '69 tank was installed? That could have also happened. It's also possible the change occurred late in the production year, but at different times by the different assembly plants.

Personally, I like the idea of the "surge tank" piece - it gives the presence of a safer and more secure set-up than the older version like mine.

I agree - never say never! I'm just providing more fodder for thought.

Randy C.

 

Yes,I get what you're saying. The car we have is a December built Lansing car,so it's before your car. I really like studying these cars and trying to find rhyme or reason why some things were done by the factory. I'm not a 68 guy but I have learned a lot about them by building this car. I'm a 66 guy but what I have learned is from taking them apart,not building them. I can't even begin to guess how many I've parted out out but I believe it's north of 50 cars.Thanks for the fodder.

 

Just a quick thanks for the helpful info on this subject. I'm in the midst of replacing the tank in my '68 442 and was a bit confused about the vent hoses. I'm confused no more.
Thanks again.

 

I've also am in the process of replacing the tank,and mine is like what Randy C. described. I don't have the gas smell after driving it, but my question is about removing the retaining ring around the sending unit, is there a special tool required ?

 

There is a tool designed for this, but you don't need it. There are these little tabs sticking up around the ring (three, I think). Tap on them gently with a screwdriver and a hammer in the direction of the circumference of the ring to loosen it. Depending on how much crud there is, it will eventually turn, and you will then see how far to turn it to line it up with the openings to get it off.

It's just a "lock ring." When you reinstall it, you'll see to line up the tabs, push down, and then turn it 45 or 90 degrees or something like that to lock it in place.

 

Thanks for the quick response .

 

My car leaks gas somewhere around the gas tank if I fill it completely on a hot day. I am thinking that the tank vent hoses may need to be replaced - but I have not had the car up in the air yet to check. I am considering adding the white plastic part that connects the 2 hoses - it may be a better design than just the 2 hoses sticking up - but I am not sure.

I don't really understand why 2 hoses are needed for the vent? It seems like a single hose connected at the top of the tank would let air in/out as needed. Both hoses connect to the gas tank and both hoses connect to the white plastic part.

Is there some difference in the gas tank connections?

or is there a valve in the white plastic part?

 

There's no valve in the white plastic piece...it's just a piece of plastic. Typically, I believe they were stuffed with some sort of filtering material. You can get the material at a local auto parts store....in the air filter area. You'll see some packages with a white Scotchbrite pad-looking material....these are the filter material for breathers inside of air cleaners but you can stuff a bit of that inside the white plastic piece. Probably put in there to keep any dirt from making its way into the vent hoses and gas tank.