Here's the deal. When I make a left hand turn you can see a trail of gasoline on the road in a perfect arc that matches the turn. I was wondering if the possibyly the vent hose came off of the passenger side tank vent allowing this to happen.

Also do you need to drop the tank to get to the vent hoses that are on the tank?

Any help will be appreciated.

1972 Cutlass S 350

 

Is the tank vented on a 71/72?
My 64 the vent is on the back of the tank, passenger side and is easy to reach.
I was having similar problems with mine, I ended up putting a vented gas cap on it and all is well.

 

I had the same problem on a 71 cutlass. I have 3 vent tubes left right and center. There is a small piece of fuel line between the tank and the steel tubing of the vent. I did drop the tank but you don't have to. I wanted to check the top of the tank for rust and other possible problems. I would change all of the rubber fuel lines at the same time. They are probably all orginal and with rubber fuel lines at 40 years is not a good thing.
Larry

 

I just had the same problem with my 71 a month ago, It was a 3" long piece of rubber hose for the gas tank vent on the frnt passenger side of the tank. Replaced it along with all the other rubber lines back at the tank, cured the problem, and got rid of the gas smell I had been smelling

 

Thanks for the info. I was hoping it would be a simple fix and the tank would not have to be dropped. This is my first project car and sometimes it feels like 2 steps forward and one step back. I replaced the hoses that connect to the standpipe assembly a few months ago and i didn't know there were more hoses or I would have replaced them at the same time. Thanks for the info, I will update this post once I replace the hoses.

 

If you gas tank is anything like my '68 or '69 4-4-2s, you don't have to drop the tank to get to those vent hoses. However, it would be ideal to put your car up on a lift so you can see up in there to work. I know I can get to those vent hoses on my cars (2 of them on the upper front passenger side of the tank) when the car is on a lift.

Randy C.

 

Well I got it fixed. 3" of 5/16" fuel line and about an hour of labor. Pulled the right rear wheel for easier access and replaced everything I could reach.

 

That vent is a strange and I think somewhat dangerous setup that GM made. If you get a fill-up then whenever you stop the gas will slosh forward and likely some will squirt out the short hoses that were used. My tank has 2 vents there and both short (6") hoses go into a Y-shaped plastic thing. The plastic tube is supposed to have a small filter in it to prevent kicked up dirt from falling back into the tank.

I am guessing that the reason for the 2 vent holes was (in anticipation of regulations) to take the gas fumes (which in fact I do smell also) that evaporate into a capture apparatus as most cars by the 80s were mandated to have.

While not strictly original for my car I have been thinking about installing one of those vapor capture canisters simply for saftey and evnviromental concerns.

 

Those two vent tubes sticking out of the front of the tank end up in different places inside the tank. One ends just inside, the other runs diagonally to the opposite corner. Both tubes are pinched shut inside the tank, but not sealed tightly. Both tubes are supposed to stay above the fuel on level ground. When the car is at an angle, the design ensures that at least one tube stays above the fuel. This means that the tank will always be vented, and no fuel will be forced out as the temperature rises. Whatever small amount of fuel is able to slosh through the pinched tube when braking will gather in the plastic "surge" thingy, then drain back into the tank.

That's the description of how it's supposed to all work. I have heard numerous stories of some reproduction tanks in which one or both tubes inside the tank are below the fuel level, which guarantees there will be times fuel is forced out when it expands.

 

Brian:
You are correct in your assessment. It turned out to be the main 5/16" fuel hose and not one of the vent tube hoses. All of the hoses have now been replaced so I should be ok for a while.

 

Brian,
Interesting. Could it be that if the tank is just topped off too high that is why I got a very minor about of dripping?

Also, no matter how the tubes run inside the tank one still get the aroma of gas as fumes will waft out!!

 

Any idea where to get that plastic "thingy" that the two hoses run into? I recently discovered the same gas leak after filling up, and found that piece was broken. Or if anyone has an idea for what makes a good substitute?

Thanks,
Ken
69 Cutlass S

 

Ken, this is called a "surge tank".

Go to the below web site (Classic Muscle) and plug in the GM P/N 403846 in the seach box. They cost $29.99

http://www.parts123.com/parts123/yb....e~cadeiijd#pdf

 

Thanks Ken......now I can get one too; I could't find one anywhere. Though I may still opt for a more elaborate recirculating system.

Incidentally, I would NOT stuff it with cotton as the site suggests. There is a type of breather assembly filter material that I think would be far safer and durable. You can get it at any auto parts store in a small package and it is very cheap.

Even if one uses the "thingy" it seems to me a good idea to extend the rubber tubes coming out of tank and run them to the back of car - about the tank level. In this way fumes will not waft up into the car's passenger compartment as easily and secondly makes it less likely under any circumstances that any fuel can splash out.