Hot answers tagged

54

Both previous posts are pretty good. I'll add a few more considerations though. On a low tank, during hard cornering, some cars will uncover the fuel pump pickup and starve for fuel. There's been some discussion for years now about keeping 1/4 tank as your minimum as the fuel provides cooling for the fuel pump. Some people argue that additional cooling ...


33

There is an unexpected effect to running with a full tank all of the time: fuel is heavy. The actual weight per gallon depends on temperature (and thus on density) but it's on the order of six pounds per gallon (or about .7 kg per liter, if you like doing all your math in base 10...). Obviously, the total weight depends on your vehicle's tank. In my car, ...


22

If you think about what the car is doing in both cases you'll see why you burn more fuel when accelerating. General theory F = mA (Force is equal to mass times acceleration), and in this case the force is applied by the engine. The more force, the more fuel is burned. Acceleration In stop and go traffic, you are making frequent stops, and accelerating ...


19

Knowing that gasoline does not freeze (Ok, it will start freezing at -180 degrees, but this is more than you or your car can tolerate) but that a small amount of water can accumulate in yout tank over time. So, in cold winter weather condition, like here in Canada, if you have a low level in your tank, that accumulated water could freeze and cause some ...


16

There are two possible explanations: If the fuel cap does not form a good enough seal, the fuel injection system may experience problems with drawing fuel from the tank. On newer cars many of them have a fuel cap sensor to detect if the cap is not screwed in. This is related to emissions, although i am uncertain how. I know when I get my yearly emissions ...


16

Every time you brake, the energy is wasted. Brakes convert mechanical energy of a moving car into heat via friction (they heat up). This is where the energy is ultimately "lost". Then, when the traffic moves forward a bit, you of course need to accelerate - and this is where you actually use gas from your tank to put this energy into getting your car to move....


12

It might cause issues with the evaporative emissions controls as the tank is currently permanently vented to the atmosphere and that can trigger a check engine light. In general it shouldn't be affecting the fuel mileage, though. The other concern is that you'll probably end up clogging the various fuel filters sooner because the lack of fuel cap means all ...


11

Regulations limit the amount of unburnt hydrocarbons that can be released into the atmosphere, therefore fuel tanks on cars now have to be sealed to stop these emissions. The noise you hear is air rushing into the fuel tank, due to the low pressure caused by the use of fuel.


9

Look up in your owner's manual how capacity your fuel tank has. Next time you fuel up, take note of the difference. In my car it's roughly 2 gallons (7.5 liters). However, realize that modern cars use fuel as a coolant for the fuel pump and running the tank dry often may damage the fuel pump over time.


9

The EPA regulations require that the fuel tank is a sealed system so that no vapors escape. There is an entire system (Evaporative Purge) dedicated to that task. EPA regulations also require that the ECM (Engine Control Module) check they system for leak. When the right conditions are met IE fuel level between 1/3 and 1/2 tank, outside temp 50 - 90 etc. the ...


9

Despite any opinions of safety it seems that gas tanks are manufactured to not accept more than 95% of their total volume because of regulations. Here is a quote from the US Department of Transportation Federal Motor Carry Safety Administration Regulation 393.67 Subpart E. (12) Overfill restriction. A liquid fuel tank manufactured on or after January 1, ...


8

If you are planning to let your car sit for a while, it also may be adavisable to have a full tank. Less air in the tank means less corrosion of the tank, if you have a metal one.


8

You will likely be annoyingly loud but otherwise fine. As always, you are liable for your own compliance with local noise ordinances. I would recommend that you drive with the windows up until you give the car to the shop in order to avoid any risk of carbon monoxide poisoning. For example, don't drive with the trunk propped open: the low pressure behind ...


8

Your engine is always burning gas when the car is running. When you're stationary, you are burning gas to keep your engine running, without actually moving the car, so you're actual miles per gallon (MPG) at that moment is 0. When you begin to accelerate, you are using more gas than when the car was idling, but then you have to press the brakes, ...


7

It's a gasoline vent tube, serving three purposes. Gasoline vapors can be especially dangerous under pressure (pretty much why it is useful), and as the temperature fluctuates it is safer to relieve the vapor pressure than it is to potentially have it build up. The gasoline vapors should preferably not be ejected onto a potential spark source (battery) or ...


6

He is correct! The actual pump is inside a canister and unless the tank is bone dry, the pump is ALWAYS submersed in fuel ( even when cornering hard). if this was not the case, the vehicle would stutter and hiccup due to air in the line. Anyone who has ever had this happen, knows it does this only when you completely run out of gas. Just look at the design ...


6

Motorcycle folks seem to do this a lot, presumably because the gas tank is easy to remove and small enough to manhandle (personhandle?). A Google search produces a lot of results for how to do this, and any of the ways you've heard will probably work well. Here's one detailed list: http://www.mopedarmy.com/wiki/Removing_rust_from_a_gas_tank You have to ...


6

The fuel pump combined with the fuel pressure regulator should take care of any air in the lines. If you don't like the idea of cranking the car continuously until it starts (it would take 3 cycles or so), then turn the key into the "on" position without cranking it. This causes the fuel pump to run, because it primes the fuel system in anticipation of ...


6

Interesting issue IF, the internal tubes have corroded within the tank that would be relatively serious. The interesting piece is, how would they corrode. As far as I know, almost ALL the fuel tanks on modern bikes use copper for this overflow. It runs from the lip above the filler point, down through the tank to a nipple on the underside of the tank (or ...


6

Yes, running low on fuel can damage your fuel pump, but as IHaveNoIdeaWhatImDoing mentioned in the comments below, modern fuel tanks are sophisticated enough to prevent fuel pump starvation until the tank is almost complete empty. Either way, damage to the pump can occur because fuel acts as a coolant for the electric motor. When there is no more fuel the ...


5

I worked at a shop that repaired fuel tanks and this is what we did. No cutting corners, each step depends on the last. The shop had a fancy caustic soda tub and some of the techs would call that an acid bath, but we used this on very few tanks. Mostly small, well constructed, steel motorcycle tanks. This is what we did for the other tanks that were not ...


5

I always let my fuel level reach near empty. Other than the cool effect on the pump, I see no advantage of not letting it get below 1/4 tank. Water is heavier than gas, so if there is any water in the tank it will be picked up by the pump first. Same goes for any debris in the tank. The pump is also situated so that on cornering the fuel pump will not be ...


5

Carry the fuel in an approved container, some local laws require color coded tanks for gasoline, diesel, alcohol etc. If you must carry fuel in the interior of the vehicle use common sense. Don't smoke, and open the windows to avoid a build up of fumes/vapors. If you are using the fuel to power a lawnmower, generator, etc carry as little as possible for the ...


5

To add a little bit to Paulster2's answer the upper and lower Explosive Limits of Gasoline is 7.6% and 1.4% respectively. This means that a concentration outside of those limits will either be to rich or lean to burn. And since Gasoline's Flash point is -45 °F (-43 °C) it's pretty much always putting off vapors, which would push any air out of the tank. It's ...


5

That pipe probably goes to the tank too, it is just there to let air out of the tank while adding fuel down the main pipe. I believe that your additive will be in the fuel.


5

There is Brake-Specific Fuel Consumption Which is a measure of how much fuel is consumed per unit energy. Another way to look at it is the rate of fuel flow needed per unit power developed by the engine. This information is not something accessible through OBD-II. But it's not very useful in this case Note that MPG remains relevant because it is a ...


5

For the sake of putting answers on questions... The WD-40 Website lists 100's of uses for the product and one of them is actually: Removes adhesive tape without damaging factory paint. So, it sounds like that advice is good. I second DucatiKiller's comment about Goo Gone or similar "citrus" cleaners. I've had good luck with them on automotive paint. ...


5

Hydrogen is an ideal gas to be used for combustion, as there are no harmful emissions byproducts if the combustion (combination of hydrogen and oxygen) is at the proper ratio. You just make pure water, which is fine. There are several vehicles and several vehicle companies which have explored the concept of pure hydrogen as a combustible fuel. The ...


5

You could take the screw out of the center of the knob. Remove it, then put it on only to shut off or turn on the fuel.


5

It sounds like you have a motorcycle with a carburetor with gravity fed fuel line. (i.e. Without a fuel pump of any sort). In those conditions I can see that there is a higher fuel pressure at the inlet to the carburetor when the fuel tank is full. It's possible that when the tank is low the pressure is barely enough to meet fuel demand. With that said, ...



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