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Gas tank capacity test

2015 Honda CR-V. The advertised fuel capacity is 15.3 gallons. Even driving ridiculous amounts after the warning light and after dead bottom on the gauge, I have never managed to get more than about 13.5 gallons back in. The only way I know of to figure out the real state of affairs (do I have 2 gallons or so left or is capacity different than advertised) is to let the tank go dry. Here’s what the manual says about that: “Running out of fuel can cause the engine to misfire,damaging the catalytic converter.” I am skeptical about that, especially if I turn the engine off at the first sign of mis-fire. The only bad thing I know of for the converter is unburned fuel or oil, which wouldn’t be happening. Is there any reason to believe Honda that I am running a risk here?

Do NOT let the tank run dry, you can cause the problems they list, along with overheating your in-tank fuel pump (it uses the gasoline for cooling). Just live with the uncertainty. Once the light goes on, refill (if not before).

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Yes, you are running a bit of a risk. Of burning up the fuel pump initially. I’ve never heard of a lean condition failing a convertor unless it is very lean for very long.

Put a gas can in the back of the car when the tank is running down with a couple of gallons. Run it until it stumbles and immediately shut the car off. Add the measured amount and get to the closest gas station, fill the tank and there you go. Take note of how many miles it took from some reference point, empty, low fuel light turns on ect and there you are.

BTW, are you just trying to prove your tank holds 15.3 gallons for some reason? Or trying to find out how far the car will take you when the gauges say “empty”?


What you’re doing is a very, very bad idea. Even the owner’s manual warns emphatically against this. I strongly urge you to stop doing it.

Personally, I never let the tank get below half. That way if I ever get a tank of questionable gas it’ll mix with the gas in the tank and I’ll probably never know I got it. And I also know the pump is being well cooled by the gas in the tank.

Why the obsession with your tank’s capacity?

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If you think about it, those two questions are the same thing.

That’s analogous to quitting drinking and driving after the first accident.

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so it sounds like you don’t have to panic when the light comes on. Cool! DO NOT run your car out of gas intentionally, even just to the point of a misfire. If that happens, your pump is no longer pumping fuel, which is the coolant for that fragile electric motor that drives the pump. If your specs for the tank is 15.3 gallons, then it’s 15.3 gallons. I promise you, the manufacturer did their math.

I should add that your FUEL light comes on before the tank is fully empty. After filling, there’ll always be air above the top of the gas pool in the tank. There are EVAP controls in that space that control the flow of air to the charcoal canister, allow the tank to breath in as the volume drops, etc. And that warning light is NOT an indicator that the tank is dry… it’s a warning to get gas before you run out or damage the pump. And it’s designed with a “buffer” to let you find a station.

In short, your tank and its systems are not designed to be totally full or to get too low.
Exactly how the engineers calculate the tank’s capacity is beyond me, but if it’s a calculation of the canister’s total volume it’ll include the air spaces above the fuel necessary for the system to function. If it’s a calculation of total volume from the pool’s surface to the bottom of the tank, it’ll still include fuel below that needed to prevent damage to the car. Either way, I recommend against your current practices.

Wow, I didn’t even mention Trump or Clinton and I get this. How happy would you be with a temperature/pressure/rpm/speedometer gauge that is correct plus or minus 9%? My desire to know my actual range (my “obsession”) seems perfectly natural. I’m on the road a lot and I like the flexibilty of picking my refueling stations. Let me ask you this: which is more obsessive; never letting your gas get below half, or wanting to know what half actually is?

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You want some one to tell you it is OK to drive your vehicle until it runs out of fuel just you can verify how much it holds? No one with any common sense is going to do that. As for obsession I also start looking for a gas station at what ever a half tank is because I don’t want to run out .

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are fuel pickups known for getting every drop of fuel out of a fuel tank?

Oh wow. You can ruin a converter in a couple minutes. Why or why would a two gallon difference matter anyway? When you get to between 1/4 and 1/2 tank, fill up and find another hobby. I’m not sure how they determine the tank capacity but I’m sure its a computer rather than filling the tank with water and measuring it.

This guys question reminds me of a thread stated some time ago, The poster was upset because he ran out of fuel more that once and his Miles to empty said 13 miles to empty.

When I acquire a new vehicle I will let the low fuel light come on. I fill up and subtract the pump reading from the factory fuel tank capacity to determine how much fuel remains when the light comes on. I have usually been driving on the top half for decades.

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Consider cutting your gas tank in half to make room for another suitcase.

You get what? A reasoned, gentle explanation as to why what you’re doing is stupid?

Every gas tank has a capacity, and a usable capacity. There’s always some gas sloshing around at the bottom that won’t be picked up by the pump. I have never had a car where I’ve run it to E on the gauge and then put in exactly the amount the gas tank holds. That is never going to happen. It is entirely normal. I have a 17 gallon tank in my TL and put in 13.5 on the rare occasions that I wait until the low fuel warning lights up to fill it.


No… “Body seems unclear. Is it a complete sentence”? No. I complied with the 10 characters. Now I need complete sentences? What next?

I also remember the poster Volvo_V70 mentioned. Didn’t make a whole lot of sense.

How badly does the OP want to know this kind of info? Either DIY or pay someone when the fuel is low to bypass the pump relay and empty the tank into a large jug. With the key on and Low Fuel illuminated, add a quart at a time until the lamp goes out. That will give you the APPROXIMATE amount of fuel remaining when the lamp comes on.
While moving you’re having to deal with fuel slosh.

A few seconds of bucking on empty will not harm the converter. As mentioned, the fuel pump is what is going to take a beating as the pump uses gasoline not only to cool but for lubrication also.
Personally, I don’t see this as being a big enough issue to worry about.

I have not a clue what that means. I therefore make a motion that we Stop feeding the Troll.


I concur…