I gassed up my 91 560SEC today, and did not fill beyond the point when the pump stopped on its own (I never do). There was no gas in the upper neck of the filler. I drove less than 2kms and bought some injector cleaner. When I opened the gas cap, a HUGE amount of gasoline squirted back at me (like half a gallon or more) and it continued slowly draining out of the open filler for the next 20 minutes (making quite an embarrassing mess of the Wal-Mart parking lot). I know liquids expand on hot days, but not this much, surely. What took up all that pressure before I removed the cap? Where is all this gas coming from? Is it harmful to any of the fuel system or anti-pollution components? Is this common and I just haven't had an occasion to notice it before? (Does my car manufacture gasoline?--I wish.)
This is the first time I heard that gas came out. I know everytime when you open the cap,...
This is the first time I heard that gas came out. I know everytime when you open the cap, you hear a sound like pressure release. But unless there is something inside you tank holding the gas up with a air bubble inside, I can imagine how the gas would shoot out.
I've never heard of that happening before. I think, like dtkw said, there is something like a pressure release. But I actually think it's not kept under higer pressure than outside, but lower pressure. It's sort of a vacuum perhaps (not sure, please correct me), and that's why you hear the sucking sound when you take off the cap. I've never opened it right after filling, yet on a hot day, I did open it after just about 12 litres had been consumed and nothing odd happened.
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I guess next time, wait until you get home first. I add Techron into my tank. Either at ...
I guess next time, wait until you get home first. I add Techron into my tank. Either at the pump before filling up or after I get home. By then, the gasoline should has settled in the tank. But still, this is something new all right.
It could have happened to any gas. Cheap gas only affect MPG and ride quality. Not if gas shoots out of the tank.... but wow, thats sort of scary to think about.
__________________ 1990 Mercedes-Benz 560SEL soon to be Euro-spec clone AMG (summer of '09) 1991 Mercedes-Benz 190E AMG (undergoing restoration: July 1 - October 17, 2008)
Don't fuel tanks have a vent for the purpose of relieving pressure?
I can imagine that if the was some kind of pressure buildup in the tank due to expansion of the fuel, and the vent was blocked, that the pressure could push the fuel out the filler.
I would suggest that you investigate where this vent might be, and what is blocking it.
I have no idea where it is, but I would like to find out.
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