72CS

I'm just about to put the gas tank back up in my Cutlass. I had to drop it to do some patch work on the rear frame sections. (I'll be looking for a new frame to put under the car sometime in the future) In the mean time, I noticed my fuel tank has four lines coming in/ going out.

One from the sending unit. (3/8" supply line???)
One from the tank kind of near the front centre (3/8" return line???)
Two lines, one at each upper front corner of the tank, (1/4"-5/16" vapour lines???)

If this is correct, can I eliminate the vapour lines (I was planning on removing all the pollution control stuff from the car anyway, except the PCV). If I removed the vapour lines, I would just run a short section of hose to join the two (nipples?) at the top corners of the tank.

oddball

Does you fuel pump have two or three lines? If three, then that extra middle nipple is the return. It's most likely vapor, though.
The vapor system is not necessarily a bad idea. The three vapor lines connect to the vapor canister behind the back seat, then a suction line from the vapor canister to the charcoal canister at the front then up to the carb.
If you nuke that, just cover the nipples with block-offs. It's hard to find good rubber for block-offs, so you'd need to check them regularly. You could use several hoses and a brass tee. You'd also have to switch to a vented cap and enjoy fuel slosh.

That should be the only emissions thing on a 72 other than the temp switch for the vacuum advance, and it's pretty minor. IMO, make sure your charcoal canister is OK, replace its filter, and let it be. I think a sealed cap is a good idea.

72CS

I was able to get the car up on jack stands this afternoon, but I had to go before I could climb under it to have a look at the fuel pump. I'll have a look at the pump and go from there. How bad will the fuel slosh, will I be pouring gas out the filler tube every time I pull away from a stop sign?

Lady72nRob71

I am trying to figure out the reasoning for removing the vapor controls. It's not like they rob power or add more than a few pounds of weight.
I like them becuse it reduces the gasoline odor when storing in an enclosed building.

72CS

I was thinking it would be a way to simplify the car and de-clutter under the hood. The lines aren't in the greatest shape and I would have to run new ones to keep the system functioning. I figured two new lines for fuel supply and return would be alot easier than 4 lines to keep the vapour control system too.

Chumley

At todays gas prices, I'm a big fan of anything that will conserve my fuel. The vapor recovery system was designed to do just that as well as prevent unburned fuel vapors from entering the atmosphere. But it's your call.

Allan R

Your car is exactly the same setup as mine. You have 3/8 and 5/16 lines. IMO you would be far better to leave everything intact. 1972 really doesn't have any 'pollution' controls on it. But to answer your question directly? If you want to plug the vent pipe at the (rear) standpipe assembly you can do that. You will also have to plug the carb where the charcoal cannister line feeds to.

The system you are taking out has no effect on the engine operation; just reduces gas vapors. The carb 'sucks' any vapors that are in the cannister to be combusted. There's a great write up on the system in section 8 of the 72 CSM. I'd read up on it before you make the changes. If it was my car? I'd leave well enough alone and call it a day.

72CS

I just got home from the movies, went to see "The Grey." Now my wife is afraid to go camping.
I haven't had the chance to get under the car to see what may need replacing besides the lines. I don't like the idea of having a car that reaks of gas fumes though. I'll have to re-think my plan. I'll re-post when I have a look under the car. Thanks for all the input so far.

oldcutlass

To answer your question, no, it will not effect the operation of your car. It does nothing to increase fuel economy. Its there to keep vapors from escaping to the atmosphere.

Miles71

My car smelled a lot when I first bought it. The problem was cracked vapor hoses near the tank.
I have since replaced all of the rubber hoses related to the fuel system. The old rubber fuel hoses do not like Ethanol fuel. So I replaced them with SAE-30R6 fuel hoses, which is designed to support Ethanol.

72CS

Well, I got it done today. Once I got a good look at it, I could see that all the lines were rotten and needed replaced. As well, someone has made their own system of hoses/ lines with splices and clamps everywhere. So, I know everyone said to leave it, but it's gone.....for now. I kept the canister and some of the hardware, so one day I will put it back in. I ran a new line from the tank to the fuel pump for now to keep my car mobile. I'll be getting a vented cap to use for now as well.
I'm grateful for everyone's advice. Where can I get my hands on one of those "Cutlass manuals" that were mentioned?

Allan R

Easier than finding the elusive Grand Pooh-bah.
Go to this website: www.wildaboutcars.com and join for free. They have the 72 Chassis Service Manual and Assembly manuals in their library of information. If you have any trouble finding the info go to the green 'how to find stuff' button on the left side of your dashboard. If all else fails, send me a PM and I'll walk you to the manuals.
BTW, while you're there - register your car in the Oldsmobile Registries. They are trying to build a database of cars still loved and breathing...

Rich Kinsley

I'm new to this site and it has been very helpful with just this first post! Thanks for the line on the wildaboutcars site. I already found the wiring diagram I was looking for.

Rich Kinsley

Zacc

Hi I have same car with no fuel return from fuel pump. how did you plug the right and left vents on the gas tank? Did you also plug the center gas tank vent going to the standpipe? How? Did you plug the hose from standpipe to the front canister ? how? I have a vented cap and no engine compartment canister. thanks Zacc

umbertoc

Allan..I hope you are well. I am going through some old threads and found this conversation regarding the evap control system on a 1972 cutlass. I have a 68 442 and the carburetor is naturally aspirated and was thinking of modifying it to remove the fuel odors. I have checked everything on the car and replaced fuel lines, carburetor, etc...their is no leaks whatsoever. Joe Padavano suggested this retrofit and i thought perhaps you might have the schematics for the ECS system so i can figure out how to retrofit. Of course...if you have any other suggestions...my ears are wide open!