Ive got a problem with the tank in my wagon. it seems that the gas in the tank is expanding so much that its driving gas out of the filler neck. the only vent in the tank is in the cap, and i assume its working since gas can escape from there. o No:
so if gas expands as much as it appears to in my tank, then do we actually get less gas per gallon in the summer than we do in the winter?
Sounds like pressure is building up in the tank. Isn't there a return line or vent tube of some kind? Perhaps it's clogged or has an obstruction in it.
Yea, thats why they post little signs at the gas station and in owners manuals of all cars that say "do not top off gas tank, expansion could occur." Also try a new cap, sometimes it can't build pressure and use the return lines and charcoal canister. :TU:
In Canada at least, There is a sign at the pumps. Volume corrected to 15 degrees celsius that would be 61 farenheit. But wouldn't consumption be on the same scale?
I'm not sure how it would affect consumption. Remember, when it's cold the air is more dense. Then you would actually get more air in the motor. It can be hard to explain sometimes. I remember when I raced ATV's, if you jetted your carb for the cold weather to be just right it would be rich for the hot weather. Less air with the same amount of fuel. But if you jetted it to be just right for the hot weather, then it would be lean for the cold weather. More air when it's dense and cold.o No: I hope it's not confusing anyone. Dan:3gears:
I worked as a Gas Jockey in 1971 and 3 out of 4 folks would always request that I "top it off". I did and by the time I racked and filled out their credit card, the fuel would be oozing from below the license plate. At .26.9 per gallon and with plenty of kitty litter in the shop, it was not a problem. In those older cars the galvanized tanks did not expand. I had a 98 Seville w/ a plasitic tank that held 18.4 gallons, by the book, and i was able to get it to take 20.
dan, i understand running rich in the winter and leaner in the winter because of the density of the air. i re jet my gs for changes in the weather. im wondering if the density of the gas is changing as well, since it appears to decrease in the summer months and thus pour out of my tank. so if you buy a gallon of gas in the winter are you getting a greater mass of gas than if you buy a gallon of gas in the summer? in any event, ill try finding a vented cap and putting less gas in .
My guess would be it's the same year round. I'm assuming that most, if not all, the stations have underground tanks, where the temperature would be more constant. It doesn't go up and down nearly as fast as the air temp does. Most of the problem is after the gas is pumped into the tank, which is warm due to the warm air. That cause the gas to expand after it gets in the tank. I would think the volume coming out of the pump would be the same. That's my guess, and I may be wrong. Dan:3gears:
the 62 wagon doesnt have return lines, a charcoal canister or a vent, only a vented cap. my 67's dont have a charcoal canister or a vented cap, they have return lines and two vent hoses. it looks like i have two poorly designed tanks, and unfortunatly i cant swaps caps between either.
No new caps are available anywhere? I used to leak gas when I accelerated. I spent under twenty bucks on the new correct cap and now I have no problem.
Yeah. Any parts store should be able to get a Stant cap for you. I bought a locking one for my '69, it took them a while to find the right part number though.
dont top off the tank. although on a wagon I dont know how long the filler neck is. i don't see how the gas can expand that much to cause a spill problem. if it's going to expand it may expand about 2 cu inches and that's alot. (a ping pong ball has a volume of 1.59 cu inches) *man am i bored* "Gasoline volume changes approximately 0.125% for every 1C change in temperature (0.058%/F) thats itty bitty amnt of expandsion." more neat gasoline info http://www.users.qwest.net/~taaaz/AZgas.html
Hah, I had the same problem after topping off my tank one hot day. Thought I ruptured the gas tank with all the gas flowing on the ground. I had no idea gas could expand so much until I put it on the lift at my shop and saw it pouring out the vent. After I parked it in the shade, it stopped leaking. Almost made me cry though after spending two something a gallon. Allen
maybe i did something wrong, but according to nate. going from 15 C to 35 C, in a 20 gallon tank would cause an increase in volume of .5 gallons. that seems like enough to fill up the filer neck.
but i thought that a vented cap would allow vapors (and liquids) to escape. since my tank doesnt have any other vent i thought it needed a vented cap, and therefore sealing of the gasket wouldnt be applicable.
