Ok, the gas guage in my c10 is not working but I figure I have about 1/2 to 3/4 tank. Went out about 12 noon, 97 degrees outside and gas is over flowing from the fill neck. The driveway is at a very slight angle so I backed up to level, no more gas leaking, couldnt even see any in the neck. Its never done this before, what would have caused it to push the gas up that high in the neck with it only 1/2 or so full? Thanks.
Likely pressure build up with intense heat, as well as the gas would "expand" Had that happen with a 51 Mercury P/up in the heat & truck not level!!!!
The angle of the car probably caused the gas to block off the fill tube that extended into the tank. With it blocked off by fuel, the gas would back up into the fill tube. Pressure in the tank was built up and when the gas filled up the tube, the pressure wouldn't allow the fuel to drain down into the tank.
I didnt think it was anything major ,it's been hot here since I got it home a couple weeks ago and its never happened. Thought there might be a vent tube somewhere that was blocked. Just thought it strange it would push gas up that far.
Gas coming out of underground tanks is give or take 55 degrees. If you fill till the vapor pressure deal shuts the pump off, then park in the sun, the temp rise in the gas is 40 + degrees. thats gonna cause a lot of expansion. If you didn't drive very far and use up a gallon or two it's gonna puke out.
I dont have leakage...but in the hot vegas heat i have a lot of 'vapor vent' outta the 54 F100. With the filler right below the door, it sure does give you some 'oh ****' moments....
Yes, this is the correct explanation. Expanding fumes from the big vapor chamber while filler pipe was "in the liquid". Expanding vapors pushed whatever happened to be in the pipe, up and out.
I picked up an old boat tank a while back and it did the same thing out in the sun, opened the cap and let the pressure off to stop it. I had no idea it even had fuel in it, what was in it was old and it wasn't full. I just ***umed the same thing, heat causing it to expand and getting to where the cap was for whatever reason.
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