Fuel level lights

[john11668]

I have two lights
7L  Amber  and 4L  red
Only the red is working and it now  does not go off when I add five litres .

I did a search yesterday and found a thread about testing the thermistors but I now cannot find it .
Can anyone remind me of the testing procedure  and what results I should get . (alternatively please guide me to that  thread)
Is the sensor unit still available ?

Going on from there and presuming the sensor is OK  what is the next step ?

[Tuco]

Most people remove the 7L light so make sure that isn't the case first.I don't know if your bike is new to you so start there first if it is.

[Chaos]

Take the flapper out then just look in the tank. 

[john11668]

Take the flapper out then just look in the tank.

I shall do that in the meantime but I like things to work!

Most people remove the 7L light so make sure that isn't the case first.I don't know if your bike is new to you so start there first if it is.

I will look at that  but I presume the red staying on   is probably due to a duff sensor .
Can anyone tell me how to test , or point me to the link about it ?

[Tuco]

If you take the flapper out you also get a little more fuel capacity.

[john11668]

Early bikes it seems had thermistors
Not things flapping about

[Tuco]

I was talking about the fuel door that the EPA mandated. My first brick didn't have one but the LT did. Makes it impossible to see down into the tank.

[johnny]

i like easing the cap back... sticking my finger in there... feeling for the fuel door... sliding 1 finger in there... sliding 2 fingers in there... pouring some seafoam in there... getting it all over my fingers... try for 3 fingers in there... take a peak in there... pull out and smell that ethyl all over my hand...

j o

[Chaos]

keepa your fingers outta my tank Johnny...me gots hot lava and crocodiles in dere!

[rbm]

Johnny, all I can say is you are one crazy motha f***r. :hehehe

I have two lights
7L  Amber  and 4L  red
Only the red is working and it now  does not go off when I add five litres .

I did a search yesterday and found a thread about testing the thermistors but I now cannot find it .

Go into the history on your browser and search for the link.  In Chrome for example, type "chrome:/history" in the command bar.

Can anyone remind me of the testing procedure  and what results I should get . (alternatively please guide me to that  thread)

There are four wires existing the sender:
Brown: Ground
Green/White: pump
Brown/Black: 7L
Brown/White: 4L

You need a multimeter with an resistance function.  Measure between the Brown/White and Brown - it should read 600 ohms at 25 degrees Celcius (about 77 degrees American Foreignheats).  Same goes for the Brown/Black and Brown.  Hopefully, these measurements are taken with the sender out of the fuel and in the air.  With the sender immersed in fuel, the resistance will be much lower.  If this is what you read, then the sensor is functioning properly.  The problem lies in the instrument cluster.

Is the sensor unit still available ?

Going on from there and presuming the sensor is OK  what is the next step ?

No, the sender is NLA.
From there, either forego measuring the fuel level and depend on the odometer. 

Or
(1) clean all the contacts in the instrument cluster as they may be contributing to the problem
(2) find another sender or circuit card to replace any failing unit.

[john11668]

Thanks  Robert
I don't have a "flapper" hence my difficulty  understanding  that term, (sorry tuco)
Will have a go at the resistances.
Mine will be immersed now so any idea what a wet reading is.
I guess a duff one will show open circuit.

[rbm]

Sorry, I got the resistance of the thermistors reversed.  Because they are negative coefficient, they should be around 600 ohms when immersed and 50 or so when exposed to the air.  Bear oin mind, these are the values when current is flowing through them to heat them up; a static test like this might yield slightly different results.  Duff ones might show open circuit but that would cause the light to always remain extinguished no matter what the fuel level -- that's not your symptom.