Gas Tank Leak??

[MidLifeCrisiz]

Daydreaming a little last night while pumping gas and filled my '71 right up and into the filler neck. Haven't had the car that long and guess never pumped that much gas in before, usually just pumped $20 worth or something. I have it running well and looking good so I pumped approx. 11 gallons last night. Stopped it just short of overflowing the filler neck by the gas cap. I then realized I had fuel pouring out over the top of the tank itself as though there is some type of vent on the top of the actual tank? :eek:The tank leaked itself down to a point that no additional dripping occurred, I dried everything off and let it evaporate for 30 minutes before starting the car. Probably let what seemed to be a 1/4 of a gallon of gas spill onto the pavement at the station. There goes $2. :disappoin

There seems to be no leak in the tank itself as it is holding on Full and no additional drips on the cardboard I put under in the garage last night. Drove it home 15 miles from the station and I can see fuel right up to the bottom of the filler neck with a flashlight beam.

My question...do I need to investigate a leak right at the connection point of the filler pipe and the tank or is there some type of vent in the top center of the tank to handle this type of overfill situation? The gas seemed to be coming from the top center of the tank and running around all four edges as opposed to right from the neck area on that side of the car. The concrete was very level where I was filling up. It is obviously almost impossible to get your arm up and feel the top of the tank without lifting the car.

Any help would be appreciated.

Thanks

Steve

[bigoak]

Take a pocket digital camera and try to get shots of the top of the tank. Note this thread where I had an issue: http://www.classiczcars.com/forums/showthread.php?t=26398

Did the spill come from one side in particular?

Given the rate of pouring out, I'd assuming you're missing something like the vent hose.

[Mike B]

Probably let what seemed to be a 1/4 of a gallon of gas spill onto the pavement at the station. There goes $2. :disappoin

Gas is $8 a gallon in Wisconsin these days? Yikes!!

[MidLifeCrisiz]

BigOak,

Good idea tomorrow I'll try and snap a picture of the top of the tank. The leaking did NOT seem to come from one side but rather directly out of the top center as it was running down and around all four sides of the tank. As opposed to where you showed in the photos on your old thread where you showed rust or corrosion on the connection seam on the tank between the top and bottom half of the clam shell...that is definitely not where my leak was occurring. It was running down off the top of the tank. I haven't had any fuel smell issues with the car and it sits in the same 3 car garage with my everyday boring to drive vehicles and the kid's bikes. I think I would have smelled it if I have a missing vent hose, never had it sitting with this much gas...maybe only a 1/2 tank but maybe we'll see more with pixs.

Mike,

NO Wisconsin gas even with our huge taxes is not $8/gallon. I believe the premium I pumped was $4.19/gallon down about $.40 in the past week that is why I pumped that much to begin with. I started thread by writing that I had spilled a 1/2 gallon and decided there was no way that much was spilled. Didn't adjust the math when I changed the amount to 1/4 gallon.:stupid:

Anyway...more to come with pixs. Thanks for the start.

[bigoak]

Mine was only an issue when filled up completely...If i ran at 1/2 tank, never an issue.

[beandip]

you have the back top vent leaking. Your tank has a few vent lines that terminate in a evaporation tank located on the passenger side to the rear of the wheel. The vent hoses enter the cabin behind the plastic panel below the rear hatch , and travel to the area next to the filler neck. To do a repair the tank must be dropped and the hoses replaced. If you do not use OEM parts , be sure the hose used is rated for GAS . DO NOT be tempted to use heater hose. Napa has 5/8'' gas rated hose. If you do a search you will find a lot of information in this area. Gary

[blue 72]

I think beandip is on the right track. I just had my gas tank out and back in this week, and there are two vent hoses on top, one on the driver's side, and then the fuel feed and return lines (mine's a '72). I've had this problem in the past, but now I know for a fact that everything is tightened down securely and not corroded or worn through. You only loose a few hours to check it (so many connections to remember and detach/hook back up). Plus, I got to fish out all the odd debris in my tank at the same time.

[bigoak]

If you are dropping the tank. Consider getting it cleaned and coated. Either take it to a rad shop or use the POR-15 kit.

[Force Fed]

A bit off-topic, but do they make new filler necks/hoses/grommets for the 240? My 240 leaks when I put fuel in, but not afterwards. Granted it was only a few gallons I put in. I figured there was a rubber filler neck hose or connector of sorts that might be leaking.

[MidLifeCrisiz]

OK got the car slightly elevated and stuck the camera up and under. Based on feel for moisture (gas) and photos it is pretty obvious that the braided line directly above the gas level gauge on the passenger side is the culprit. This braided line runs up toward and next to the filler neck. Seems that I could get up and disconnect on the tank end...where does it go after it heads over by the filler neck? Is this the same line that ends up in the filler neck that you can see when you open the gas cap or goes to an evaporation tank? Has anyone replaced this line without dropping the tank?

beandip...

your comments about the evaporation tank...where is it located? Is it above the hatch deck in the quarter panel so I can access by removing the interior plastic or do I get access from underneath the car? Don't want to pull the interior apart just to investigate. This leaking braided line goes up and toward the passenger side as you described, but seems I could replace without dropping the tank. I can access the hose clamp connection on the tank without dropping it.

Does anyone believe this isn't my issue? You can see from the pics that the line is wet where it connects to the top of the tank. I assume that this line isn't supposed to be porous but rather braided for flexibility...correct?

bigoak...Thanks for the help and the idea about using the camera.

Learning something new every day...better than a day in the office!

thanks

Steve

[Mike B]

A bit off-topic, but do they make new filler necks/hoses/grommets for the 240? My 240 leaks when I put fuel in, but not afterwards. Granted it was only a few gallons I put in. I figured there was a rubber filler neck hose or connector of sorts that might be leaking.

It looks like Courtesy Nissan still has the filler necks.

http://www.courtesyparts.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=CP&Product_Code=17208-S3074

For the hoses, search for a post Arne wrote up a post about which hoses are better to buy EOM and which can be replaced with non-OEM.

-Mike

[26th-Z]

Hey MidLife!

Your vent hose is broken and you pretty much have to drop the gas tank to replace it. The Evap stuff is behind the quarter panel over the passenger shock tower. When you drop your gas tank, look for manufacturer markings on the top of the tank. You may find something interesting. I can't believe there isn't a fuel system diagram posted in the archives. This problem has been discussed a million times. Very common problem.

So how's Wisconsin? I grew up in Mequon. Go Packers.