Are GAS FUMES the secret to better gas mileage?
February 5, 2012 by Admin
Filed under Discussions
Sometime ago I read a recommendation somewhere that I fill my car’s gas tank when it reaches the half way mark, and if not then, definitely by the time it reaches the quarter mark. I wondered about the wisdom in that recommendation because I felt that the extra weight of a full tank of gasoline would reduce my gas mileage. But I read on, and the writer pointed out that gas fumes (rather than gas-fluid) are ignited create power. The thinking Seemed to be that when the tank is fuller, there exists more gas fumes to burn, and fuel injectors are quite efficient Although spraying a fine mist into into the ignition chambers, this gas-mist is not quite as fine as real fumes. The net of it is that filling your tank sooner provides more fumes and the injectors are viable Therefore to do a better job. Tested this a couple of times and it seems to work. Got 44 as opposed to 35 mpg on highway for a few gallons, and 28 as opposed to 26 mpg in city for a half tank. Your thoughts please. Additional details: Car is a 2008 Toyota Corolla LE. Has about 3000 miles on it. For highway driving test, I filled up, drove about 80 miles at 55-60 mph, and returned to same gas station, same pump, and filled up again. For city driving test, I filled up, drove around town for a week or so, and then filled up again. My driving was pretty much in the 30 mph or less range.
Fumes are what explode with gas. Gas itself doesn’t. Fumes are dangerous. Reguardless if you fill your tank or half full you gas mileage with only vary about a half mile a gallon or less.
Fuel is taken from the tank in liquid form, through the fuel line. Any fumes exit through the filler neck when you open the cap to refill it. These fumes likely contain a negligible amount of energy.
The reason people say not to run a tank all the way down is so sediment that has collected at the bottom of the tank won’t get sucked through the fuel line, potentially clogging this or that part of the fuel system.
Your fuel line exits from the bottom of the tank, and liquid gas is pumped to the fuel injecters, which then atomize the liquid into vapor. I suspect you changed your driving techinique when you were consciously thinking about fuel consumption, and that would improve your mileage.
I’m with David. It’s just not possible. The fuel pump is not designed to move air. It only moves liquid. Also, it is desgined to take in liquid fuel from the bottom of your tank and pump it to the engine. No matter whether your tank is half full or all full, you are not sucking in any fumes.
You were most likely being very much more careful when you tested your theory and as a result you got better fuel economy. I do this alot. When I am being careful my car gets about 37MPG. When I am late for work and racing around I get 30mpg at best.
Your engine doesn’t run off gas fumes. It runs on the liquid gasoline that is pumped from the tank to the engine by an electric fuel pump (usually) located inside the tank.
The reason to keep your tank full is because air from the outside enters your gas tank as fuel is consumed, and the outside air contains moisture. As the outside air temperature cools at night, this moisture from the air will condense inside your gas tank, and leave a layer of water at the bottom of the tank, to cause rust and the potential for your fuel pump to pick up water instead of fuel, which will cause your engine to run rough (or not at all.) If you keep your tank full of gasoline, there is less room for air and less moisture to condense and cause problems.