I finally managed to hit 400 miles before the bar started blinking. I did this by waiting till my previous tank (which had accepted 8 gallons) dropped down by 3 bars and then filling it up again, getting in 4 gallons. Yesterday it was down to one blinking bar at 400 miles with an average of 51.7 mpg. Of course the tank then proceeded to only accept 6 gallons. I think i'll make it a tradition to let every other tank drop by a few gallons and then fill it up again. It seems to help me squeeze in more gas. Someday I will get 500 miles on one tank!
SULFUR CAN CAUSE GAUGE PROBLEMS!!! And since all I've ever is low-sulfur gas, that could very well be the reason why my gauge has always worked perfectly. We need to constructively prove or disprove the effects of sulfur on the setup in Prius, starting with the following... http://news.yahoo.com/news?tmpl=story&u=/a...s/sulfur_in_gas Fri, May 28, 2004 By ALAN SAYRE, AP Business Writer NEW ORLEANS - Just before the heavy-driving Memorial Day weekend, Shell Oil has stopped the sale of gasoline at more than 500 of its stations in the South because of high levels of sulfur that can damage vehicle fuel gauges and make an empty tank appear full. The damage done by the bad gasoline could cause some drivers to run out of gas unexpectedly. Also, car owners may have to replace their fuel gauges — a repair job that can easily cost $400 to $600. The tainted gasoline originated at the Motiva Enterprises refinery in Norco, La., according to Shell. Motiva is the refining arm of Shell in the East and South. The company said it is investigating how the high sulfur levels occurred. Sulfur is naturally present in crude oil; some of it is supposed to be removed during refining. As of Friday, 119 Shell and Texaco stations were closed in the New Orleans area, and 400 were not selling fuel in Florida, said Shell spokeswoman Helen Bow. (Shell owns the Texaco brand.) Gas tanks have a float ball that rises and falls with the fuel level. An electrical system reads the float ball's level and transmits the information to the dashboard fuel gauge. The system uses silver electrical contacts, which can be quickly corroded by sulfur. The problem came to light this week after drivers began complaining about inaccurate fuel gauge readings. In addition to the New Orleans area, problem fuel turned up in shipments to Miami, Tampa, Sarasota and Fort Lauderdale, Shell said. Shell is replacing the gasoline at its stations. But Bow did not have an estimate of when all the stations would be pumping again. Don Redman, a spokesman for Louisiana AAA, said that before the shutdown was announced, he fielded several calls from the auto club's members complaining that their gas readings were way off. "People have been looking at their odometers because of the high prices and saying, `Hey, wait a minute,'" Redman said. Shell said it had received 1,800 queries and 825 claims from people who said their fuel gauges had been affected. Guy Valvis, owner of an auto repair shop in Metairie, said he normally handles about two gauge replacements a year. "I've fixed three or four here in the last week, and I've got two in here right now," he said Friday. Valvis said the repair job entails draining the fuel and removing the gas tank.
Stung again by the moody gas gauge Sigh....stung again by THAT DARN GAS GAUGE! I was so excited - anticipating my first 500 mile tank. Then...I woke up this morning and my gas gauge had gone from 4 bars to 1 bar in less than 24 hours with only about 40 miles put on it in that 24 hour period. :x On the screen last night - 50.3mpg, 345 miles (it had been 305 when I went to work yesterday morning), 4 bars showing. This morning when I started it up: 50.3mpg, 345 miles and 1 bar showing. Average temps have ranged from 88 during the day to about 64 at night, the bulk of the driving is during the day. Does anyone have a clue as to what is going on?
I can't explain it, but almost the same thing has happened to me twice, but mine went from four bars to two bars completely skipping the thired bar. Jeff
Well, I'm thrilled that my post generated so many replies and so many interesting theories. However, I haven't experienced the same thing again and just fill up every 400 miles or so - I don't do stress anymore, at home, at work, or while driving. By-the-way, I bet the Prius doesn't use a ball float method to send the tank contents to the display. That would be just too crude. My guess is that it's some sort of titanium plated plazma duct that reacts to solar particles (muons?) and their irregularity causes the problem depending on how many granite bridges you pass under each day.
Thought I'd add another data point. We got our prius last week (built in 04/04) and finally had to fill the tank yesterday. I was purposely waiting until it got to the blinking bar before filling up thinking that (and I have no really good reason for this) sort of like batteries in laptops and portable devices, maybe the bladder has a sort of "memory." Keep waiting till the tank is nearly near empty and you'll be able to do the same tank after tank. It sounds crazy to me, but I work with computers for a living and I long ago learned that things don't always act in a way I can comprehend. In any case, my wife was driving when the bar started to blink at about 495 miles, which seemed to make since given that we'd been getting about 44-45 mpg. She pulled over within a mile or two and managed to get 11.3 gallons in the tank. If she hadn't kept the receipt I'm not sure I would have believed it, but divide 495 miles by 11.3 gallons and you get 43.8 mpg, almost exactly what the computer said we were averaging. The weather here in Texas was probably in the lower to mid 90s at the time and I highly doubt this was low-sulfur gas like john1701a uses. Of course one fill-up doesn't make a pattern, and we might have just gotten lucky. We'll see how it goes next time.
Another trip ended with less than 2 gallons possibly in the tank, and two bars on the gauge. Each time I empty the tank quickly, I don't get told to fill up. When I do it slowly over a few weeks, I get the warning way before 2 gallons are left. Perhaps the bladder dislikes stale gas?...
OK I don't have a Prius yet but I have been following the debate with some interest as one day I will have one. Is it possible to siphon the tank and find out how much is left in the tank? Has anyone done this? That’s is where I would start. Henry Drygas
the 'darn gas guage' used to be a concern to me, not knowing when to fill-up when it blinks, how many more miles i can get etc. but i guess i just learned to live with . because of the varying temperatures here (hot during the day then sudden dip overnight) i'm not surprised anymore by the gauge fluctuations. i've become comfortable with filling-up at 400miles (gauge blinking already), which always takes 9gallons, knowing this, i dont worry about it anymore. i could push it for another 100miles but i dont bother. :wink: