14 liters plastic tanks not holding 14 liter. Comments?

[Howie]

If you only consider the external size of the filter, pump and lones that would add up to a lot of gas.  Fact is these components are full of fuel.

[stopintime]

Does anyone have any idea why the "reserve" light comes on at about 1,5 liters (30 km) left instead of 3 liters? It shouldn't be related to the volume issue. Have you heard anyone replacing or adjusting it?

[Ducatiloo]

However there is a least a litre left in the tank below the level of the fuel pump inlet.

That is what drives me crazy, if I have to haul around that gas I should be able to use it.

[Howie]

Does anyone have any idea why the "reserve" light comes on at about 1,5 liters (30 km) left instead of 3 liters? It shouldn't be related to the volume issue. Have you heard anyone replacing or adjusting it?

Because they screwed up?  You should probably be glad the dang thing works. Usually they fail in the on mode, forcing you to live with a useless, bright yellow light.   Your trip meter is your friend.  Learn to use it an consider the low fuel light an "oh shit" light like the oil pressure warning light.

Replacing it probably won't help.  They all seem to be off by the same amount.  They are also expen$ive.  The units are sealed and considered not serviceable, therefore theoretically not adjustable.  I never had one to tried to take one apart though.

[stopintime]

Because they screwed up?  You should probably be glad the dang thing works. Usually they fail in the on mode, forcing you to live with a useless, bright yellow light.   Your trip meter is your friend.  Learn to use it an consider the low fuel light an "oh shit" light like the oil pressure warning light.

Replacing it probably won't help.  They all seem to be off by the same amount.  They are also expen$ive.  The units are sealed and considered not serviceable, therefore theoretically not adjustable.  I never had one to tried to take one apart though.

Howie,

"glad it works"    sounds good enough for me

(congratulations on the upcoming 1k posts!)

[Capo]

Here is a fuel level sensor from a steel tank, the wires at the bottom of the pic are the connections for the fuel pump.



Inside the tube is a float that rides on a center pin



The float has a movement range of approx 16mm, and appears to influence the resistance of a coil contained within the tube, when measured the resistance of this coil decreases when the float is in the lower position. This probably means that a comparator circuit in the dash triggers the indicator lamp when the resistance of the circuit falls below a set value.

Therein lies a way to 'calibrate' the point at which the low fuel light comes on.

[Popeye the Sailor]

Those lights fail all the time anyways. Just get used to using the trip odometer, so the first time it fails, you won't find out the hard way (like I did).

[somegirl]

I just use the trip meter too.  Everytime I get really good mileage I think that my light has failed.

[ducatiz]

Those lights fail all the time anyways. Just get used to using the trip odometer, so the first time it fails, you won't find out the hard way (like I did).

In 20+ years of riding, I've never had a fuel light go.  I have a second-hand 1985 Alazzurra which still has a fully functional fuel warning light -- it has a manual reserve tap tho.

I guess I am lucky?