Quick question. Since I've had the Prius, I've always run the gas down to one pip before refilling. I refilled about a week ago. I have driven about 150+ miles and the "pips" are still on full. Given my mpg (around 54) I figure I'm down around three gallons. I want to top off today because we are leaving on a driving vacation tomorrow. I have this vague recollection of reading something about topping off screwing up the gas gauge. Is that true or is my brittle old mind playing games with me again?
The short answer is yes it can be harmful to your car and the environment. http://www.epa.gov/donttopoff/
But aren't the pips and topping off two different issues? The pips are an unlinear representation of the amount of gas left in the tank. Topping off is the practice of pumping fuel into the tank after the nozzle has clicked off. So paflyfisher could try pumping gas into the tank and then just take care not to force it in if the nozzle clicks off.
I think he means filling up again after only driving 150 miles, not trying to squeeze more into the tank once the pump clicks off. I haven't tried it yet, but I've heard it may not register correctly on the gauge. Mike
<div class='quotetop'>QUOTE(mikel 52 @ Sep 8 2006, 09:29 AM) [snapback]316270[/snapback]</div> Yes that's my question. By topping off I meant adding back the 3 gallons or so that I have used even though the gauge still says full. Bottom line is with the 3 additional gallons, I can make it to when I want to be with stopping for gas. Without the 3 additional gallons, it would be a stretch and I would probably have to stop before I want to. So again, I am not talking about overfilling. I am talking about filling when I am only down about 3 gallons.
That's what I thought you meant (though I admit that my reply wasn't terribly clear.) "Topping off" is a term that refers to the practice of putting more fuel in the tank after the nozzle clicks off. Most gas pumps have stickers on them that warn not to do that for reasons mentioned in the EPA link above. You're just talking about filling up your tank, which I wouldn't hesitate to do.
The gauge does not seem to "see" the top 2 or 3 gallons. You should be able to fill your tank again, as long as you obey the usual advice about not attempting to add more gas after the nozzle shuts off. I cannot imagine how this would hurt the gauge. Of course, you'll probably make it another 150 miles before the top pip goes out. I once tried to fill my tank after using less than half. It was a convenient stop on a road trip. The nozzle refused to put in any gas. But I think it was an overly-sensitive nozzle. And this was before I had the filler-pipe recall work done (which affected some 2004 Priuses).
If you're going to be driving 400+ miles you'll need a bathroom break, and a gas station is the perfect place for that!
Geez, it's a simple question - let's not warp off about global destruction and the end of life as we know it. You're not going to hurt anything by filling the bladder when it's not empty. The fuel level sensor is inaccurate to begin with, and you're not going to make it any worse by filling up before you leave. I've added less than three gallons three times, for exactly the reasons you state - I know I can save a stop if I do so. I've also added 1.8 gallons with right around 80 miles on the tank because I knew I wasn't going to see gasoline anywhere near as cheaply where I was going. The "fuel level" gauge acts the same if I put 1.8 gallons or 9.8 gallons to fill the bladder.
If you put in a small amount of gas, the only thing that will happen (unless you get a very sensitive nozzle that already thinks your tank is full) is that your MPG info will not automatically reset. Once you fill, you can hit the reset button (on the Consumption screen) to have your tank miles traveled and mpg set back to zero. Have fun on your trip!
