Could either of you explain "Strain" on the fuel pump.

 

Don't run it to empty. Problem solved.

 

Generally the gasoline is used to cool the fuel pump because it is submerged in it. If the tank is near empty the fuel pump is exposed allowing it to heat up, possibly shorting its life span.

This may not be as big a problem as it was in the past, but some people still feel that keeping the fuel pump submerged is better for it’s operation.

 

The fuel pump probably uses the gasoline to lubricate it , Just like an aeroplane tank, since its immersed in the liquid. getting too low could starve the pump and cause premature failure.

 

glad i didn't have the problem on my month long trip... on my way home looking for a gas station i ran my gas tank down to 2 and 15 miles left... gas stations are rare on some roads... :(

 

Thanks for the explaination on "strain". My son-in-law is a BMW master tech I'll ask him about the premature failure issue.

I took a road trip and ran down to 9 miles left. Filled up the tank with 13.5 gallons in the 13.2 capacity tank!??

Oh well, I don't think I'll let it get down anymore.

 

most i've filled up was 13.5, and it was in the red and down to 20miles left.

 

I know that the gauge on my is kind of screwed up. With 3 lights out, if I fill the car, it takes about 7 gallons. So it's about 1/2 a tank. I would be nice if there was a calibrate the gauge.

 

djam43,You have explained that perfectly. My wife, bless her heart had a very bad habit of running her Audrey A4 on fumes. After 3 years of this just before the lease was up the fuel pump croaked. Thank God it was under warranty. Best of all my wife has learned the lesson I couldn't teach her.

 

If the pump is lubricated by the gasoline *passing through it*, totally running out of gas would remove the lubricant and damage the pump, but there's also the theory that the pump is cooled by the gasoline *surrounding* it, in which case, even letting the fuel level get too low (without running out entirely) could damage the pump by uncovering it in the tank.

I've never looked inside a MINI gas tank, though, so I don't know if the pump body itself is actually immersed in the fuel, or how low you'd have to run the tank in order to uncover it.

 

Yes it cools it too & you are 100% correct Scott. My wife never ran out, but was always running her A4 on fumes.

 

That's probably because you topped off and there was fuel in the filler neck, which is not part of the tank size computation.

Of course, there is always the possibility that the pump is not calibrated properly.

 

I took my Mini to 27 miles left to go, one bar. Decided not to push it any further, filled up and it took 13.5

 

How does running your tank level lower than half a tank put stress on your fuel pump?

 

why would one let there gas tank get that low. all you do is unsettle all the deposits on the bottom of the tank and end up clogging up your filter and or injectors. I always fill mine when it hits a 1/4 tank.

 

Maybe half a tank isn't dangerous, but it helps not to get close to trouble if you want to avoid trouble. One bar is definitely too low for me. If I see two bars left, I'm definitely headed to the nearest gas station.

 

you are correct. most pumps are in the tank so the gasoline can cool them off. they are small though and would require only a couple gallons to submerge them enough to keep them cool. the only time you would do damage to them is if you constantly kept a low tank.

 

So the question then is, how far down into the tank is the pump itself?
Diagrams would help illustrate the issue.

 

"Risk Takers" unite. It's these little gambles in life that keep it exciting. Anyone can fill up at a quarter tank. This discussion is about the human personality. Some people go for it some just sit on the sofa and watch it on TV.

 

I have not ever seen a linear gas gauge in the cars I have driven. The needle moves slowly when full but it speeds up as it goes down.

 

I think that's more of a safety cushion, as you never know when you might go for a while with no gas available or no time to fill up.



My reasoning has always been the lower I run the tank, the less amount of time I spend in a gas station, which is not a quality portion of my life.




In my CRX I would often 'challenge' myself to see how far I could go. Fortunately it was light enough that I could push it into the station when I ran out just before entering. At some point I tired of running out of gas and started filling up. I think the moment of change was running out on Christmas on the way to my fiance's house.:impatient

Note that the fuel pump is now pretty noisy, but it's still pumping at 205K/23 years.

 

I thought I would add this to the discussion. A full tank of gas is like running around with an extra person in the car. At over 8 lbs per gallon, a full tank of gas will be almost 100 lbs. Does it make a difference? Maybe a little bit. My best so far is 36.6 mpg for a complete tank of gas at 70 mph with two persons in the car. (Which the Magellan actually says is 67 mph)

 

Actually, it's *water*, not gasoline, that's 8+ pounds per gallon. Gasoline is closer to 6.25 or 6.5 pounds per gallon.

Surprisingly, the weight of your car isn't going to have much effect on your fuel economy *on long highway drives*. It will make a difference around town, where you're constantly changing speed, but even then, the gas in your tank is a fairly small fraction of the total weight of the car + driver.

 

As I see it NO GAS = NO JOURNEY

 

youll make up for the longer duration inbetween stations with a nice week long stay in the dealers bay while your getting you injectors swapped out at over a grand!
Ill take the 1/4 tank rule and motor on!