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Discussion Starter #1
So I've got a 2000 156 SW 2.0 TS. As I understand it the fuel tank capacity is 63L + 7L reserve tank. On this logic, based on my average economy of around 7.5L/100km I should be getting somewhere around 800km - 850km to a tank (~500 miles).

However last night I filled the car up as the fuel light had come on and only 43L went into the tank before I couldn't put any more. The last time I topped up the tank it was 39L. Seems very odd to me that 20L would somehow go "missing".

So is this just a matter of the gauge being incredibly inaccurate (which I know they are) or is there something I should look into? Whether it be a faulty gauge, fuel level sender etc?

Its quite annoying having to keep topping up the car every ~550km!
 

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Thought it was 63L including the 7L reserve.

As for only getting 43L in when the light came on, not unusual.
You'll get to know how far you can risk going once the light has come on.
 

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Discussion Starter #3
Ah yes you might be right about the 63L including the 7L reserve. So I should still be able to get somewhere around 100km - 150km extra out of a tank. Might have to buy a 10L jerrycan and just run the car and see how far before it starts coughing on me to work out roughly how far a true full tank will get me.
 

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Yes. I knew I could get from Lincoln to the Shell garage on the A14 at Fenstanton with the light on.
That is 85 miles and it wasn't empty. I didn't like risking going further though!!
 
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In my SW, I've filled 68L before, 65L on some occasions. My fuel light is VERY pessimistic and comes on while I could drive close to 150km (90 odd miles) If I fill straight after the light comes on, it'll be less than 60L
 

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Once you have filled the tank with engine running or just switched on ECU could not count add and stayed the same. Actually real quantity of fuel inside the tank may be bigger than actual reading.
It is a normal story for cold country than you want car warms faster and do not switch it off while filling.
To correct it is needed to disconnect battery and check again. Hope this will do.
 

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I believe the Fuel pump, as my wallet feels how much I pay for the fuel I put in.

One fills the petrol tank until the pump stops (i.e. the petrol tank and pipe to the filler cap is full). It has nothing to do with the ECU and having the car on while you fill will use maybe another 100ml of fuel in the time it take to fill it - really an irrelevant quantity either way (positive or negative).
 

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Discussion Starter #8
In my SW, I've filled 68L before, 65L on some occasions. My fuel light is VERY pessimistic and comes on while I could drive close to 150km (90 odd miles) If I fill straight after the light comes on, it'll be less than 60L
Sounds similar to my car then; being a pessimist that is. Was just double checking to make sure it wasn't just me who seemed to have a fuel light that came on incredibly early! I know they are notorious for being inaccurate but 20 odd litres seemed a bit strange but apparently not!

So thanks all. Now I know to just ignore the bloody thing until around 650km or there abouts :thumbup:
 

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This is the official info:

Petrol tank capacity: 63 Litres, inc 7 litres of reserve
Alfa Romeo 156 Handbook

Plus one might add couple of litters in the filler neck pipe (or maybe less). I would suggest that if pump 'sells' 68 litres, than it might need a calibration, or even a trade authorities visit if it is a deliberate set up.

Last week I drove for about 70-60 miles with the low fuel light on with the constant speed. Something close to 62 litres went in (need to double check) and my mpg was 52.3 if I remember correctly.
 

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The 7 litres is included in the 63 litre capacity.

The actual capacity would be slightly more, as the 63 litres does not necessarily included the litre or two in the fuel lines and the fuel filler neck if you brim the tank. But not 70 litres. Maybe about 65 or 66.

The light is *supposed* to come on when only 7 litres are left, so you should be able to get about 56 litres into the tank.

So you've got 13 litres "missing", not 20 litres.

That may well just be inaccuracy in the gauge - maybe you were driving up an incline and the fuel sloshed away from the float for long enough.

In my 156, the light often comes on, but when driving the car again later, the light will be off again.
 

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Try parking on a curb with wheels half on half off. You'll find you either have more or less depending on the incline and how the car's banked ;-)
 

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As many of you know my car runs on LPG but my fuel gauge for petrol still goes down whilst running on gas. Someone told me Alfas use the on board computer to calculate the remaining fuel through your current MPG and it only takes a float reading on filling up.
So even though I have half a tank of fuel after 2 days of driving it shows empty even though I still have half a tank.
If this is the case could that be where your missing 13 litres are? You actually have more fuel then the gauge is telling you?
 

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As many of you know my car runs on LPG but my fuel gauge for petrol still goes down whilst running on gas. Someone told me Alfas use the on board computer to calculate the remaining fuel through your current MPG and it only takes a float reading on filling up.
So even though I have half a tank of fuel after 2 days of driving it shows empty even though I still have half a tank.
If this is the case could that be where your missing 13 litres are? You actually have more fuel then the gauge is telling you?
I don't think this is the case on the 156 at least. I have always found mine to be pretty reliable, if ignoring the coming-and-going fuel light near the end of a tank.

Once mine properly shows empty, when I drive it until it's that low, it's always somewhere from 55 to 60 litres going into the tank.
 

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My gauge used to go down to empty, light on, it would then go up to 1/4 tank again, then down to empty with light on again.
You didn't need to fill until light on for 2nd time..... fine as long as you didn't miss it when it came on the first time!!
 

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My light has never come on. I've owned so many ropey cars I've got into the habit of always brimming the tank and resetting the mileage. Firstly this lets you calculate mpg so you can see if something's amiss and you can guess when your tank might be emptying. Don't think I've ever exceeded 600 miles on a tank so it's possible my warning light may actually be working.
Slightly off topic; does anyone's car tell them when the windscreen wash is low? Even my 1986 sierra had this basic feature!
 

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Slightly off topic; does anyone's car tell them when the windscreen wash is low? Even my 1986 sierra had this basic feature!
I have never once driven a car with this feature...

That being said, I keep a litre of pre-mixed screen wash in the boot.. If it runs out whilst I'm on the move, I top up next time I'm parked up..

Consequences of running short of screen wash are much less severe than any of the other fluids mind, so it's understandable that we don't bother with it.
 

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I have windscreen washer sensor with my 159.
As I learned, it is compulsory option when you order car with headlamps washer.
:biglaugh:
 

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Ive also run lpg in a 147 and now 166. Fuel gauge behaves the same when on lpg. Stays static as no actual petrol is being used.

might be different in a 156. But id expect the same results really.
 

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Doubt it. If any install is dodgy its mine.

But why would the gauge move if no fuel from the tank is being used. It would pump it round and return it. Therfore the float would stay near enough static.

The only time it might look for it to drop is when I hooned the 147 round and it would estimate a lower reading becasue I was doing about 15mpg. Therefore it showed less fuel to show you it won't last long.

Same as the fuel range. Ever noticed your range gets further after 10 mins of driving. This is mainly becasue the engine has leaned the mixture out and works out average mpg.

If you do an average of 20 mpg then it would last 100miles. If you do 30mpg (Once warmed up) you get 150miles.

Then you let the car cool. Start the car again. It say's you've now got 70 miles left in the tank. This is because the engine is doing a cold start therefore works out again if it continues to run rich that's all you have. Then it warms. Leans out the mixture and you are back up to 120miles. etc etc etc.





LPG it stays on the same range though. As it's using no petrol...
 
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