Peugeot 307 Fuel gauge
- Thread starter maltaron
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Totally a wild guess here but a fuel pump squirts in a deluge of fuel, and shocks the float gauge into action - but if the juice is just trickled in, maybe it doesn't sense it so quick?
Either way, once the fuel was shaken around in the tank during driving it would register soon enough.
John
Either way, once the fuel was shaken around in the tank during driving it would register soon enough.
John
I had a peugeot 405 with exactly this problem, only the fuel gauge used to sit at three quarters of a tank and not move, the only way was to look in the mirror, then do a succession of emergency stops to get the fuel sloshing around, the gauge would then show true reading, usually a quarter of a tank.Totally a wild guess here but a fuel pump squirts in a deluge of fuel, and shocks the float gauge into action - but if the juice is just trickled in, maybe it doesn't sense it so quick?
Either way, once the fuel was shaken around in the tank during driving it would register soon enough.
John
Wotan
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This won't help much, but I know that the fuel gaue is part of the "CAN" system. It doesn't work like a conventional one where the float moves an arm on the end of which is a variable resistor, and the resistance is sent to an analogue gauge.
Instead, the float sits on an arm, on the end of which is a variable resistor, and for some reason best known to Peugeot, I think the car takes an instantaneous reading from the variable resistor as soon as the driver's door is opened (or maybe as soon as the ignition is turned on) and it then ignores the float resistor reading for the rest of the trip! The gauge is fed with information from the ECU, which counts how many times the injectors have fired, and therefore "calculates" what ought to be left in the tank. This gets round the problem of fuel gauge indicated level constantly changing as the car moves around and the fuel sloshes about. That's why you don't get a period where the warning light flashes on and off as you accelerate, brake, or go round corners. It "calculates" when you've got about 100km left, and puts the warning light on. When it comes on, it won't go off again until it has seen a decent change in level. I think the handbook probably says that the gauge won't register changes of less than "about 10 litres", so all I can think of is that you might have put 9.9 litres in from your can, and 10.1 litre in at the filling station? Either that or on the occasion when you filled it from the can, the float level was almost at the bottom of the position where it would next register an amount of fuel (being a analogue device that has readings converted to digital values, there will be a finite "resolution" for the system - whereby it is programmed not to recognise increments below a certain value), and when you filled from the pump, it just happened to be near the top of a "segment", so it jumped to the next digital value.
(Reading all that, it hardly makes any sense to me!)
I first found this out with a Peugeot Partner hire car that had to be returned empty. Having been on the warning light for quite a while, and having a plane to catch, I chickened-out and put a couple of Euros in it, and was dismayed not to see any movement in the gauge whatsoever! That lead to me chickening-out again a few miles further on, and putting another couple of Euros in it (with the same result)! I bet the hire company knew this and were cynically exploiting it!
I think Peugeot just assume that people will run them until the light comes on and then fill them to the brim each time.
Instead, the float sits on an arm, on the end of which is a variable resistor, and for some reason best known to Peugeot, I think the car takes an instantaneous reading from the variable resistor as soon as the driver's door is opened (or maybe as soon as the ignition is turned on) and it then ignores the float resistor reading for the rest of the trip! The gauge is fed with information from the ECU, which counts how many times the injectors have fired, and therefore "calculates" what ought to be left in the tank. This gets round the problem of fuel gauge indicated level constantly changing as the car moves around and the fuel sloshes about. That's why you don't get a period where the warning light flashes on and off as you accelerate, brake, or go round corners. It "calculates" when you've got about 100km left, and puts the warning light on. When it comes on, it won't go off again until it has seen a decent change in level. I think the handbook probably says that the gauge won't register changes of less than "about 10 litres", so all I can think of is that you might have put 9.9 litres in from your can, and 10.1 litre in at the filling station? Either that or on the occasion when you filled it from the can, the float level was almost at the bottom of the position where it would next register an amount of fuel (being a analogue device that has readings converted to digital values, there will be a finite "resolution" for the system - whereby it is programmed not to recognise increments below a certain value), and when you filled from the pump, it just happened to be near the top of a "segment", so it jumped to the next digital value.
(Reading all that, it hardly makes any sense to me!)
I first found this out with a Peugeot Partner hire car that had to be returned empty. Having been on the warning light for quite a while, and having a plane to catch, I chickened-out and put a couple of Euros in it, and was dismayed not to see any movement in the gauge whatsoever! That lead to me chickening-out again a few miles further on, and putting another couple of Euros in it (with the same result)! I bet the hire company knew this and were cynically exploiting it!
I think Peugeot just assume that people will run them until the light comes on and then fill them to the brim each time.
