the most ive done is 60miles with the light on, i got to the petrol station and it started to sputter, on that day though i got my car to go 352 miles all city drivng, now thats nerve wrecking.

 

also consider this.. your pump is cooled partly by the fuel inside the tank... if u run it low... its going to suck up more trash and run hotter... im sure its not going to kill it instantly but im sure it doesnt help extend its life any..

Fuel pump $380
gasket $15
2 hours with my hands in a full gas tank...

umm i keep mine with at least a quarter....

 

Sineo - HR = heart rate

1Move - give it up already, radio shack.

 

I try to avoid letting it drop into red. I went down to ware it said 20miles left two days ago only to find it wasnt bs'ing me at all. Put 16.7gallons in the bloody tank lol. Red means red get your a%% to a gas station.

 

If the pic in your sig is your home driveway... you're parking on a slope. As previously pointed out many Audi's use a float, so it'll only be accurate when the car is level. -- They typically when a float is used they put a delay in the gauge so you don't see notice the gauge go up/down as you drive up/down hill.

As an anecdote, my '87 used a float that after 15 years or do developed a small hole in the bulb. So the float would slowly fill up with fuel. If I ran the tank below 1/4 it would start to drain and work for a few days after filling up the tank. Then the float would fill up again and sink to the bottom.


The one time I ran my '03 until engine shutoff and it felt to me like the computer shut the engine off rather than the typical surges and sputters a car gets as the last of the fuel sloshes around in the tank.

The part that is the worst for the fuel pump is the pump running dry. So if the computer did actually shut me down that problem may be avoided in the newer Audi's. To be safe though, I still primed the pump and the lines a few times by turning on the ignition for a few seconds (not hitting the starter) turning it back of (and repeat) before starting up the car.

I'm not a fluid dynamics engineer, so I may have some terms wrong, but there are some basic physics to why running low on gas is bad for the pump. When the tank is full gravity creates a head pressure at the pump. The fuel above the pump is "pushing" down on the pump, which is at the bottom of the tank, and helping push the fuel (to some degree) through the lines. As the level of fuel in the tank goes down the head pressure at the pump goes down. To maintain a constant flow (constant gpm and constant psi) physics deem the pump will have to work harder.

However, fuel pumps generally only have two settings: on and off. So when the tank is full the pump delivers the maximum amount of flow, and the flow decreases as the stress on the pump increases. In theory, at any given point the pump is delivering more fuel than the engine can consume; the excess is returned to the tank. As a side note, this is why cars with the stock fuel pump typically seem to have more zip when the tank is full, there is a noticeable difference in the pressure in the fuel lines.

The point is, that increased stress isn't generally good for mechanical devices. Don't get me wrong, the fuel pump is designed to work at all levels of fuel commonly expected in the tank. However, all things being equal, the increased stress of running the tank near empty will have a cumulative effect and may decrease the life of the pump.

Running a modern fuel pump dry isn't nearly as devastating (as mentioned earlier) as running the diaphragm (manual) fuel pumps dry. But think of it this way. The pump is a motor, and like any motor it is designed to run with a certain range of stress (load) on it. When the pump runs dry you remove just about all of the load as the impeller spins free. You wouldn't rev your engine to 6K in neutral and just keep it there for 5 minutes would you? The analogy isn't very good as there are _many_ different factors at work, but the idea is the same.

 

Ummm....the pic in your signature (i.e. your boost gauge) SCREAMS Radio Shack, so be careful what you say!

 

Remind me never 2 buy a car from u guys cause i know the first thing i'll be replacing.lol

 

i usually run mine down to just uner the 1/8 mark cause im a teenager and i dont have alot of money lol but i noticed if i let the car sit in a perfectly level place ill leave the car and come back with more or less gas then when i started then once i drive it a lil it goes back same thing when i fill it itll go wayy past how much i put in the go back down

 

I drove about 25 miles with 0 miles left the other night. Not my finest moment, but there just weren't any gas stations around. I won't be trying to repeat the experiment, but it's good to know. I personally think the Audi ran on love for the last 15 miles or so...it loves me so much that it didn't want to leave little ol' me stranded on an empty Texas highway at 4:30 in the morning. It's a theory.

 

I don't let my cars and try and not let my bike go below a quarter of a tank. .02