I took a business trip over to Atlanta today. 393 miles roundtrip and as I approached home the Distance to Empty (DTE) started blinking and said I had 45 miles left and by the time I was home it was 38. Now the manual says the tank has a 20 US gallon capacity and I have never been able to get in more than 15 gallons when filling up with the guage on empty.

Are there still +/- 5 gallons? I noticed that there is another value for Imperial gallons of 16 5/8. Are service stations now measuring in Imperial?

I don't mind a bit of conservative slack in the guage but I'm wondering what leeway there really is.

 

I ran my Z until the low fuel light (by the gas gage) came on. I then filled up and discovered I had 4 gallons left (based on a 20 gallon tank). So, for me, my reserve when on empty is 4 gallons. this may vary from Z to Z.

 

Driving back from Florida I almost ran out... At least I thought I almost did. I was on 95 at 1:00 am and could not find a open gas station. The DTE light came on and said 30 something, then 10 miles later started blinking with just --- lines and no miles. I drove about 20 mins like that and finally found a station open. The car still only took 18.8 gallons so I still had another 1 or so. Its not good to let it go that low but thats the most it ever took to fill the car and I drove at least 35 miles with the light saying 0....

 

Yeah the 20 gallon thing threw me off as well. I ended up overfilling it since I had only put in around 16 or so gallons. I was also wondering about the mentioned imperial number.

 

Same thing: my first fill-up was 14 gallons, with the DTE reading 85 miles. Even at 20 miles to the gallon, I should have been good for another 120 miles.

 

I guess the only way to figure this is out for sure is for one of us to drive until the tank is completely empty. However, that wouldn't be good for the car and I am sure non of us would like to get stranded somewhere.

 

the tank is 20 gallons, they are the same gallons the gas stations use....



but yeah, I took it down to 40miles to empty, and put 15.6gallons in, at 20miles a gallon, I had almost 100 miles left... yet it said 40. thats a leeway of like 50miles. not the worst thing in the world.

Im sure it saves a few people.(see 4 posts up)

not to mention you never want to run your tank dry... there COULD be crap floating in your tank, that will never hurt you till you suck up that last drop with all the crud in it.

 

The car makers today don't want you to run the tank down till you're on fumes. The fuel recirculates from the pump to the engine and back to the tank (minus what gets injected). The pumps are submerged in the fuel which also cools the pump. If you run too low the pump may start to cavitate due to low inlet pressure and high fuel temp. This can cause bubbles in the fuel line and pressure variations leading to driveability problems and higher emmissions due to incorrect fuel delivery. Also, the pump could overheat in really hot weather.

Imperial gallons are only used in England and perhaps some ex-colonies. Canada used them up to about 10 years ago. I know of one marina in Whitefish Falls Ont (pop ~50) that still dispenses in imperial gallons. One imperial gallon equals 1.20095 US gallons.

 

I remember from a previous thread that the general consensus was about a 3 gallon reserve?

I also remember people having problems with filling the gas tank the whole way, and I've been watching for this every time I pump gas. so last time I pumped at about 3/4 or 4/5 empty, it only filled 10 or so gallons. I thought, no way, now i have this crapass problem too, and kept on trying to fill more. Finally I just gave up, started the car -- it was above full. Oopss... just happy it didn't overflow.

 

That's exactly why I kept on putting more gas in. I've read about the filling problems and since this was my first time doing it, I didn't know how much room I had left. I wasn't as fortunate as you though since I spilled gas all over the place.

 

As an update, I filled up this morning and put in 17 gallons with the DTE showing 28 miles as I pulled into the station.

I can deal with this. Kind of like my 69 Dodge Dart. When the tank said empty you could still go farther. Saved me when I was a kid.

I agree with a previous poster that it is not good practice to drain the tank and get crud (water) into the fuel system.

 

Dr. Gallup makes a valid point.

It occurs to me, as well, that I did not pump beyond shut-off. With reserve fuel, gas still in the line, and perhaps half a gallon still to pump, the DTE probably is more accurate than I thought.

 

Actually the Z runs a non-return type system. Only a supply to the fuel rail, there is not a return line. This is kind of unique as there are very few cars that run this type of setup.

Last I checked oil, aka fuel, floats on water not the other way around.

 

Don't get too confident about having a reserve of 3 or 4 gallons. You may not be able to get the full 20 gallons in. Your tank configuration could give you a 1 or 2 gallon air bubble, cuttiong the usable volume of the tank to 18 gallons. I learned this the hard way on an old Supra, when the light comes on, it is better to pay attention to it.

 

Yep, you're right. If you have water in the bottom and run the fuel down too far then you get water.

 

Right, and why I try to keep my level above 1/4 or more, it used be to 1/2. Also, never fill your tank when a fuel truck is filling the station's underground tanks and you don't want ANYTHING that stirs up, go somewhere else if you can. If you are really low, put in 1 or 2 gallons and go fill up elsewhere.

 

hmmm never thought of that, good advice.

 

Good advice Boomer, how often does a station clean out their tanks, probably never. If you drained your car tank after a couple years you would be amazed how much water and crap was in it. Not keeping your tank filled also allows condensation to build up.

 

Once or twice a year, I put Heet, the gasoline antifreeze which soaks up water, in the fuel tank when its under 1/4 tank, fill it w/gas and get rid of most of the water. The stuff really works, I know it for a fact. Others may want to try it, if they don't already use it.

 

Thanks for the info, I didn't know that. Returnless is a less expensive system (no return line) but may suffer from some driveability problems, particularly vapor lock the first hot day in spring while the service stations are still selling winter grade fuel. Many other potential problems which hopefully Nissan has worked out.

Does anyone know what the fuel rail pressure is? Does the system have a fuel rail pressure sensor? Has Nissan done this on other vehicles? I hope this is not their first vehicle for this system! I am a fuel injector design engineer and I don't like returnless systems!