Why can't a gas tank feed from both sides?

We risked running low on fuel today, and saw the car sputter briefly while going up a hill. Made it to the gas station fine, in fact with a gallon to spare, it seems.

I presume the gas lines in this car drain from one low spot in the gas tank, but when it's on a slope and very low, there's no fuel there. Why can't we have a series of drains at both back and front (and even all 4 corner points.) It would have to go down from there to stop air getting into the fuel line from the exposed fuel outlet, which may be the reason this isn't done, since the tank is usually down low for various good reasons. Could a smart valve allow for any hose exposed to air to close so that air doesn't get in the line?

I guess stalling going up a hill might not be the end of the world in most places, since you can go down to a flat part and start again, but in a "U" you would be trapped.


yes, and while we're at correcting the utter stupidity of gas tank design, how about a fuel gauge hooked to a trip meter so we can see
how many miles we've gone SINCE the stupid idiot light went on...!

When I read the subject, I though "Oooh, great idea" -- but what you described wasn't what I thought it was.

I was recently told by an auto mechanic that, at least in my car, the fuel pump is inside the fuel tank, and it uses gasoline for lubrication. As a result, running with the fuel level low is a bad idea, comparable to running without oil in the engine. Any implementation of your idea would have to allow for this.

I suppose a cone-shaped tank would solve the problem, since the low point would remain the low point over a broad range of angles -- but that creates the problem of having a pointy thing full of gasoline sticking out under the bottom of the car.

The idea I thought you were going to discuss was having fuel intakes on both sides of the car, so you can pull up on either side of the pump. At a crowded station, I've often had to drive around the pumps to get the intake next to the pump. When I drive a borrowed or rental car, I seldom remember to check the position of the intake before pulling into a station, and I typically guess wrong and have to pull out and back in again. Adding an extra intake on the other side should solve this and allow for more efficient allocation of cars to pumps at gas stations.

While it is annoying, many pumps, especially those who have the hose on a retractable cord from the top of the pump, about 7 feet up, can readily reach both sides of your car, unless you have an RV or really big van or truck, but sometimes even then.

My cap is on the driver's side (which is most common.) At Costco gas, there is usually a line, but there's quite often a much longer line at the lanes to the right of the pump (for driver's side intake) than on the lanes to the left. And quite frequently there will be a line for the right side and NO line for the left.

So I pull into the lanes, position my car with the tail by the pump and pull the hose over my car to fill. The hose doesn't touch my car, though it would not be a killer if it did.

Sometimes I ask people with driver's side gas cap why they are sitting waiting in line, and they can see me filling my identical car on the other side. They say it just bugs them to do it that way, and it seems they would rather wait. Bizarre.

I thought that too! And it would be a boon. Most cars in the UK have the cap on the right side, and so there is often a queue, so it isn't just where you are that has the issue.

The other guy is right, of course, pulling in the "out" gets you past all that, and on some cars you can reach the hose round, but they are usually about 6" too short for me, and the nozzle winds up the wrong way.

In the States you get service fuel stations and handy clicker things that let you just leave it to fill the tank too. Not over here, not any more. :-(

I have noticed that in most cars I have driven that if the gas gauge in the dashboard is on the left side of the speedometer the gas cap is on the left, if the gauge is on the right side of the speedometer the gas is on the right, obviously I haven't checked every car on the market...

My Ford has an arrow below the gas gauge pointing to the side of the car with the gas cap, very nice. It's worth taping a little arrow to your dashboard for other drivers if your cars manufacturer wasn't so considerate.

No, the question is why is the fuel pump in the gas tank to begin with? The answer, so they can charge $300 to replace it.

Isn't it simply a matter of which direction you pull in from? ;-) I've yet to see a gas station that restricted which side you could pull in from...

There is often a line (always when the other stations are not doing a price war that drives them down to costco's margins) and in any event, it is always one way and one way only through the pumps. There are a few other big stations like that.

When I want to use the lane with the shortest line even though my tank is on the wrong side I just drive backwards up to the pump. I'll put up with funny looks to save the time.

At least half of the time that I swipe my debit card through the reader at the store, I've done it the wrong way. I will stare at the picture showing me how the card is supposed to go through for a long time, and manage to convince myself to put it in the opposite way.

Would it kill them to build card readers that let you swipe the card in either orientation?

I've thought about this issue myself, but in reading your article I realized that there really is only one drain needed and that would be a the lowest edge of the rear of the tank. If you are going downhill and run out of gas because the drain is sucking air you could easily just coast until you got to a level area and then the gas would flow again.

The main reason for not implementing these ideas is cost. It is simply not cost effective to have 2 or 4 lines leading out of the gas tank when 1 does the job just fine, not to mention you would then need 2 or 4 pumps. Not that I haven't done it many, many times, but you should never allow yourself to run that low on gas in the first place, especially if you know it's a problem with your particular car. My car never has any problems like that, so maybe the tank is designed better, in which case it comes to simply doing a better job in designing the tank rather than "jury-rigging" a needlessly complex and overly expensive system. I also originally thought it was meant for two intakes, one on either side of the vehicle, and tho it is a good idea, it may not be too aesthetically pleasing, and once again, it is not very cost-effective.

The problem that you are posing to fix has already been "fixed." Fuel tanks have a "reserve" basin in the middle of them. The fuel pump draws from this basin, and it is the last part to go dry. It is hard to explain how this works, but anybody that has ever replaced a fuel pump knows what I'm talking about if they looked inside the tank.

Picture looking down in the tank:

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As the tank gets low, gas sloshes around, running from end to end. This box has simple valve mechanisms that allow gas to enter, but not to leave -trapping gas inside the 3" high walls. This is where the pump pulls gas from. That is why you can drive around on less than 1 gallon of gas. Without this you would not be able to go up a 2% slope without at least 1/8th of a tank of gas. Your vehicle sputtered going up the hill because the slope was so steep that the gallon left in the basin was all on one side, away from the pump's inlet sock.

Never drive your vehicle this low on fuel! The post about pumps using gas for "lubrication" is not entirely accurate, it servers as more of a coolant for the pump. Also, during winter years if you always have a low tank of gas, there will be more condensation inside of the tank. Fill up when you hit half a tank if at all plausible.

Are you joking? - just don't let your tank get that low. It can be really dangerous for you and your car to run out of gas.

I think cost might be the reason for this. It is really not feasible to have more than one. Would to hear everyone else's thought. Glad you brought something interesting.

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