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Discussion Starter #1
Hi all, I have a carbed Blackbird which the low fuel light has never worked on it since I got it. The fuel gauge works but not the light. I haven't even looked at it yet, have been having to much fun on it! Is it an LED or a bulb? Looks like an led. Anyone have this problem before!
 

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This is not really an answer to your question but... I believe that the low fuel light (LED) and the fuel level sending unit are what one might call a "duplex" system. They share the same mounting platform on the under side of the fuel tank yet they function independently of each other. I notice that my low fuel light will begin to glow slightly as the fuel gets down near what I believe is close to empty. I know that on site we mention and describe the low fuel light as "coming on hard" at xxx number of kilometers or miles. This is due to the nature of the lights ability to somewhat glow at a low ebb until the fuel level is truly beyond the reach of the probe that makes up the sensor for the low fuel light system. The attached parts fiche shot shows the intergrate assembly that makes up the fuel level sending unit and the low fuel light. The fuel level portion can be seen as a thin rod attached to the float device on the end. The low fuel light sensor is the other probe which seems to be wound with another coil of wire or some such around it's length. I believe it functions by measuring the diff in resistance that the fuel presents due to temperature,.a themistor is perhaps in use (read this on the net..so I know it's true..?...) . When the probe is uncovered the cooling effect the fuel provides is gone..the themistor temp goes up and then light comes on when the resistance on the themistor drops with the increase in temp ..or something like that. Yes..with thermistors when temps go up the resistance drops and voltage goes up...and so the light comes on. This may be in part why the light tends to come on slowly with a low glow and then glows brighter as the fuel level drops. Mind you this is all guess work on my part. I know this..the whole fuel level sending unit system/s are rather delicate and it is not difficult to alter the state of tune of the sending unit without even trying.

Case is point: I believe that even as I took extreme care in removing and re-installing my sending unit in a new fuel tank from the old that the peformance of the send unit changed by degree. Everything still works fine,..but the manner if which it works some what changed. I notice the fuel level indication stays around the "full" hash mark longer and then tends to suddenly drop off rather dramaticly as the tank seems to get below half a tank or more. This after being extremely careful to not bend/snag/catch the probes and float on the install to the new tank.

A google search will turn up hits on "how to repair the low fuel light" on my Goldwing...Suzuki XYZ and others. Many of these fix include a trip to Radio Shack for a new thermistor to replace the unit with. This saves the expense of ording up a new complete sending unit. Here's a link to one of these chat session related to the Goldwing:

Low Fuel Level light sensor GL1500 How to Fix #93975 - Steve Saunders Goldwing Forums

The easy fix is to first to check in the LED has given up the ghost. If you could access the underside of the empty fuel tank you could test for output from the fuel sending unit perhaps?

Tony
 

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I thought so of mine also. The gauge will read almost in the red, and no light. So I go to fill up. It only takes 3.6 gallons. The tank will hold an easy 5, and the light comes on when there's a gallon left. I verified mine works by jumping the connector and sure enough, it comes on. I personally don't like letting my tank get down that far :)
 

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I'm regularly running to the chicken light but then again I am filling up at least once a week so little chance of any crap building up.
 

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Discussion Starter #6
The previous owner told me it was broken when I bought it so I presume it used to work for him an then stoped working. The gauge hits the bottom and usually takes 18.5 liters or so. The 96/97 blackbirds tank was 1 liter smaller than all the others so that's 3.5 liters left. I get 240kms to 260 before I fill up. I will run it to 280kms this time and see but I'm sure it's gone. I hope it's just the led, cos if it's the internal sensor I will just leave it.
 
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