Yep, I always wait for the light to come on, and then a wee bit more as well!
The Saxo can do well over 600 miles to a tank (45 litres) and I take a sad pride in seeing how close to 700 I can get it!
The Scenics computer runs out of miles with about 6 litres still left, good for another 50 miles or so.
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.Many moons ago I had to empty andclean out the fuel system on a Lancia coupe. >It never ran properly again.
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The idea that a car doesn't run properly on very low fuel is a load of old cobblers IMO, I do it all the time either through no fault of my own at work or in my own cars and i've never had ANY problems.
A Lancia coupe that never ran properly again? It probably never ran properly in the first place.
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I am sure this has been covered before but, whilst on this topic, where exactly is the feed from fuel tanks to engine? If it is at the bottom, then surely it doesn't matter how low you run it as any particles will be at bottom and will get sucked into pipe even when tank is full?
If it is just above the bottom then surely the fuel will run put before the particles can get sooked up into the engine?
Unless is it the case that the particles float?
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I'm sure this is why fuel filters were invented!!
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Running low drags up the rubbish/fuel filter blocked. miles away from getting a replacement.hence probs/need I say more?
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Steve
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A Lancia coupe that never ran properly again? It probably never ran properly in the first place.
Not fair Mr Imagos. If a car has never run below 1/4 full then all kinds of smeg will be in the bottom of the tank. If you routinely let it run past empty from new then the cack never gets a chance to build up.
Following a challenge from another JTD Alfaowner I have been running for 75 miles with the warning light on and still had a nominal 3-4 litres in the tank. Previously I've not gone past 50 miles.
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Not fair Mr Imagos.
Maybe i'm wrong but i think this 'if you run low on fuel you suck up all the rubbish in the tank' really is a myth.
For one how exactly does leaves or sand get into the fuel tank? I'm sure most petrol pumps must have some sort of filter.
If these impurities were in the fuel or the tank had some sort of sediment, the movement of the car during normal driving would mix it all together and it wouldn't matter whether you had no fuel or a full tank.
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The idea that a car doesn't run properly on very low fuel is a load of old cobblers IMO
Not in my experience.
Your car probably has a good clean fuel system, imagos. An old MkI Astra that I bought off my brother-in-law (never, never again..) didn't. It was never happy; often losing power, eventually cutting out momentarily. No-one could work out why. It gradually got worse; eventually it would cut out at the worst possible moments and refuse to restart for a few minutes.
It was sheer good luck that I mentioned this to a mechanic who was working on it and immedately he cleaned the carburetter (someone spell that for me, please!) which was full of muck. His advice was to avoid letting the car run low on fuel; given its mileage and history the tank probably had more muck sloshing around at the bottom. And when the fuel ran low, it went into the carburettor and stuck in the jets; no fuel flow, no power.
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I worked for an MD who had a Ford Scorpio 1989 vintage. He ran out of fuel on motorway. We refilled from a can bought from a filling station. Next week the car had to be garaged as despite fuel filters the injectors were blocked with fine silt - presumably from the bottom of the tank and dredged up with the last fuel drops.
Note: fuel injection, filter and yes it was regularly serviced (a company car 2 years old some 75,000 miles or so).
I run to 1/4 and then refill. Too many journeys to Scotland at Bank Holdiays to risk running out of fuel late at night with no petrol stations open between Perth and Dundee or Dundee and Aberdeen.
With fuel injected diesels to run out of fuel means to have to purge the system of air: a sometimes complex job I would NOT want to do...
madf
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Some diesels have automatic priming ;o)
Alfa, anyone?
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And whenthe fuel ran low, it went into the carburettor and stuck in the jets; no fuel flow, no power.
I'm sure we've discussed this on another thread. The fuel pickup is the same height from the bottom of the tank at all times. How come it suddenly starts picking up crud when the fuel runs low?
Doesn't make sense to me.
As for filling up, I use Texaco loyalty points so I fill up at the local Texaco place whenever possible, or if I'm out of the area, another Texaco station if the fuel gauge is below a quarter full.
Hawkeye
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Stranger in a strange land
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is the same height from the bottom of the tank at all times. How come it suddenly starts picking up crud when the fuel runs low? Doesn't make sense to me.
My thoughts exactly, This has to be near the top of top 10 motoring myths.
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Hmm.. the posts which have had low fuel running problems seem to be carburettor fitted cars. This can't be a coincedence?
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Assuming there is crud in the bottom of the tank, where has it come from? The fuel? Surely not - don't the companies supply a "pure" fuel or at least fuel that doesn't have crud in it? The tank, maybe rust when tanks were made of steel, but aren't most made of plastic now which surely shouldn't react to form crud should they? Or am I showing my ignorance of fuel and tank technology? Is there really much "crud" in the bottom of a tank?
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Only one way to find out really. Get a tank out of a modern car and swill it out to see what in the way of crud appears :-)
teabelly
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Actually, about tens years ago I did, for parts, scrap an old BX RD given to me by a french bloke( the front subframe crumbled to pieces as I removed it) It had about half a tank of diesel which I emptied into a container, it looked OK with no crud that I could see, so I put it in my BX TGD and it ran perfectly. The tank was plastic.
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Not in my experience.
>>It was never happy; often losing power,No-one could work out why. It gradually got worse; eventually it would cut out at the worst possible moments and refuse to restart for a few minutes.
>>And when the fuel ran low, it went into the carburettor and stuckin the jets; no fuel flow, no power.
>>
I had a similar experience but due to water from a filling station tank getting into my tank. The fine rust from my rotting tank got through to the carb and even blocked the fuel line. A difficult clean of the fuel line and a new tank was required.
This may be an extreme example but a fuel filter, even if it is routinely replaced, will not collect crud for ever and will not stop a fuel line getting blocked so why risk running on a low tank.
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Whenever you pass a Supermarket or other outlet with a bargain price then fill up, regardless of how much is left in your tank even in it's still half full. This way you save the most money in the long term and get the maximum fuel for your expenditure. Leaving the tank to go empty forces you into the hands of petrol retailers who know you have to stop and fill up regardless of cost eventually (an extreme example being the motorway services who have a captive market). The fuel will not be wasted as you still drive the same distance and consume it as normal, howeve by doing this your can take advantage of the most competetive price when you see it, therefore exercising choice.
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With a 70+ mile reserve I can take my pick of diesel retailers. Running with 80kg less in the car saves fuel as well (full vs. empty tank)
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Actually, running near to empty makes the car faster and more economical than keeping the tank full or nearly full. 55 litres of fuel add quite a bit of weight to the car, and that takes more power to push and increases fuel consumption. Which is why racing cars sometimes run out of fuel before the finish, even with massively powereful F1 engines they don't carry even half a litre more than they have to,
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Sorry ND, duplicated the point you made. Moral: Read before posting!
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At this point I'm tempted to paraphrase the saying that an optimist is one with a quarter-full tank, while a pessimist is one with a three-quarters empty one.......
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Actually I have just carried out the experiment someone advocated, for different reasons, on two separate cars.
1) Triumph 2000, carburettor. The pipe runs straight out of the bottom of the tank, to a filter on the fuel pump. No crud in this 40-year old tank. If there had been, it would have gone straight down the pipe regardless of the fuel level.
2) Volvo 240, injection. Pipe dips into the tank from the top. It doesn't quite reach the bottom of the tank, and has a filter sock on the end. No crud visible. If there had been, it couldn't have reached the pipe anyway.
Conclusion - the whole thing is a myth.
Explanation of apparent occurences - air locks, low fuel level shows up ailing petrol pump, habitual low fuel level encourages condensation = water droplets in carburettor.
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1) Triumph 2000, carburettor. The pipe runs straight out of the bottom of the tank, to a filter on the fuel pump. No crud in this 40-year old tank. If there had been, it would have gone straight down the pipe regardless of the fuel level.
I'm not an engineer and have in the past mentioned that my mechanical suggestions and suspicions are usually no more that. However, I can see how a fuel pipe at the bottom of the tank could be protected from detritus except when the level is low.
We have assumed that the flow into the pipe is smooth and uniform at all times. This assumption may hide a lot. The crud will, by its nature, be heavier and less prone to shift. When the tank is full, fuel could well flow out but leave the crud undisturbed at the base. Fuel will flow from the bulk liquid, and the flow velocity at the edges will be low.
When the fuel level is very low, it will then need to flow "through" the crud; hence the local flow velocity in that area, the base of the tank, will increase. Hence more crud in the fuel line.
Now, I'm assuming that there is crud in the tank, and this is of itself a potential problem. We have counterexamples, in the form of clean tanks. However, 6 white swans in a row does not prove that all swans are white. Likewise, some tanks could have been allowed to become less than pristine. How? No idea, but I'd like to know so that I can avoid it.
All I know is that after a life of supermarket petrol and the tender loving care of my brother-in-law, that car started being an utter nightmare after the tank was allowed to run low....
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Surely the act of putting fuel in the tank is going to stir up the mythical crud that's lying in the bottom of the tank? If that's so, then shouldn't we let the car stand for 10 minutes to let it all settle before driving off?
Load of old cobblers.
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Would depend on the flow rate from the pump, the flow pattern when it arrived, where it came into the tank, where the mythical evil stuff prefers to hide etc etc
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Sorry to repaet myself! But if there is crud, what kind of crud is it and where does it come from?
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Seeing as no one else wants to say it - it's car pixies dust. We've proved it can't be from the plastic tanks or the fuel, so it's the only explanation.
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The handbooks tell me that my Golf has a 7 litre reserve, the MB 9 litres and the Capri 10 litres. These seem adequate quantities to me in terms of delivering fuel without dragging up bottom-of-the-tank nasties, which is presumably why the fuel gauge is set as it is. I normally fill up when the needle reaches the empty mark and before it enters the reserve zone; if I'm some distance from a filling station, I know how far I can travel.
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I rely on my 'distance to empty' reading rather than the fuel guage and light. I fill up when the value drops below the range needed to reach my destination (I have yet to travel anywhere >450 miles from my starting point). So, in the week I fill up around the 30 miles-to-go point or near the start of a longer journey at a known cheap filling station.
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I have to put super in my car, so if I'm away from home I do start to get a bit nervous as the needle passes 1/4, since not all garages sell it. I have actually bought a can of octane booster so that, in emergencies I can use normal unleaded, but I'd prefer not to use it, since it cots £11, and a half fill of the tank would require the whole lot. Now THAT is an expensive fill-up!
Around my local area though, I wait until the light comes on, then go to my local Shell garage the next time I'm passing it.
Oh, when I was driving around SW USA I basically filled up the moment I passed a station, if I was anywhere around or below the half-way point. I had no idea when I was going to see a station, and didn't fancy breaking down in the middle of Death Valley :D
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I wait until the fuel warning 'bongs' at me, I then have about 8 lites left - very loud, always unexpected so frightens the wife. It annoys you as it bongs every time you start up and the warning sumbol takes up the screen showing other info. I then put in a fixed number of litres - usually 15 as this lasts about a week - then see how many miles I get until it bongs again - it's a good way of keeping track of mpg.
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Surely the act of putting fuel in the tank is going to stir up the mythical crud that's lying in the bottom of the tank? If that's so, then shouldn't we let the car stand for 10 minutes to let it all settle before driving off?
Load of old cobblers.
I agree. Not to mention the movement caused by cornering and braking.
I pour in a small bottle of additive each time I fill the Triumph with unleaded fuel. This mixes very effectively using what is technically called the "sloshing around effect". How does the alleged crud avoid being sloshed around, but sit obediently waiting for the one time in 10 years when I inadvertantly run the tank empty?
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Must just be me who is sad, but I never let mine fall below 1/2 a tank. Maybe this is because my Dad always runs his on empty and has so many times found the local garage either closed or out of unleaded.
I have taken a petrol tank out of a car in the past and there was a lining of crud in the bottom of it and the fuel pipe was actually blocked with similar. The car didnt have a fuel filter fitted but I would imagine that if it had that too would have been blocked with gunge.
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I haven't thought about this too much. I wouldn't be able to tell you how may miles to the gallon I get in my car - or anything like that.
I put petrol in in a strange way (according to everyone that knows me). I never put more than £20 in at a time. When the light comes on, or if it is going to come on imminently, I whack £20 in the tank. It's never been filled, and never been topped up with more than 1/4 in. I suppose filling the car makes it a lot heavier so would waste fuel but this isn't the reason for my filling habits - my Mum and Dad do the same.
Another spanner in the works - I've read this thread and some people never let it go under halfway. What are the implications of mixing say, BP petrol and Sainsbury's finest? Or is there no problem at all.
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Adam
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Before anyone get's in with the joke, I don't literally stuff a £20 note into the filler neck.
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Adam
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Before anyone get's in with the joke, I don't literally stuff a £20 note into the filler neck.
Might be cheaper. Anyone know the calorific value of a £20 note vs the teaspoon of petrol that £20 buys?
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No idea but a bottle of Jack Daniels works a treat - 6 months ago that would have been a waste but now - it's cheaper!
;-)
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Adam
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>>>>>>>No idea but a bottle of Jack Daniels works a treat - 6 months ago that would have been a waste but now - it's cheaper!
Eh what? I pay just under 10 quid for a liter bottle of sippin' whisky, and 24.5p for a liter of gas.
Damn car gets filled to the top every Friday come what may.....
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owie, you're right about running low on gas in unfamiliar surroundings. On Maui my wife and I rented a Ford Escape V6. Set off for Hana with probably a bit under 1/3rd of a tank left expecting to fill up on the way there. After all, it's the USA, right! Long story short, we didn't pass a single gas station. The last 15 miles, the light was on the whole way and trust me that V6 was thirsty. Hana turned out to be incredibly rural. One solitary gas station open _every other day_ with I think just a single pump. Fortunately, we happened to be there on an 'open' day, although the gas as you can imagine was at something of a premium.
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