How to test a fuel light?

Hi everyone,

I sold my 81 xj650 and picked up a 85 maxim x, which I love. Anyway the low fuel light is not working. I have checked the bulb.

I measured around 11.50v comming off the green wire from the bulb. Just wonder how to test the sending unit its self?

 

unplug the sending unit. use a jumper on the chassis/harness side. the light should turn on.

 

So I crossed the wires going to the bulb and it lights. So I decided to pull the unit out of the tank.

I found the wire on the unit broken off. I soldiered it back on but it still doesn't work. Looks like I'll need a new one

 

what do you mean it doesn't work? why should it be on? how much fuel is in it?

 

With the tank drained after I repaired the wire on the sender, the low fuel light won't come on

 

I might be wrong, but i think it needs to see a reflection for it to come on. So in other words, the light turns on when the tank is between 5 and 30% full. At 0% full, it won't turn on. I know mine did not work when empty, but works now when coming down from being full. Fill it up and let it drain into a gas can. See if it comes on before empty.

 

I will. Thanks for the tip

 

ohm meter will tell you too

 

Well before I "fixed" the unit i mesured the continuity which of course was 0 because it was broken. Now that its been repaired, checked out side of the tank its 3.77??