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Discussion Starter · #1 ·
Okay so my fuel indicator light stopped working this past weekend. Finally got around to doing some tests. Apparently something in the gauge cluster is not working causing the low fuel indicator to not come on when the fuel level is low. According the section 7-33 of the shop manual this calls for replacement of the entire gauge cluster. Is there any way to fix the existing gauge cluster? Everything else works fine except for the low fuel indicator.
 

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Not sure what tests were performed, but it is common for the fuel level thermistor to crap out, uncommon for the gauge electronics to fail.

If you haven't already, you can try to artificially activate the low fuel light by grounding the R/B gauge wire, and/or activate the very low fuel light by grounding the B/Lg gauge wire.
 

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Discussion Starter · #3 ·
Hi TeeRiver. That is the test I did. The R/B wire works with fuel level flashing, The B/Lg wire did not come on. The shop manual calls for replacement of the gauges in this case.

Since the R/B wire did work should the flashing fuel warning stay on even when fuel is at the very low levels or would it stop working once it's very low?
 

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The fuel sensor is a dual type. The flashing light should go out when very low and the other circuit take over. Might be worthwhile to remove the thermistor and check the solder joints and also to trace the B/Lg wire and check for continuity of the B/Lg wire.
 

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Discussion Starter · #5 ·
I did check the continuity at the guage connector, per the manual, and it checked out good. Only thing I did not check is the fuel level sensor. Probably will do it this weekend. I will check continuity at the connector at the sensoe as well. Thanks.
 

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Might be worthwhile to remove the thermistor and check the solder joints
99% probability the solder joint has cracked on the upper sensor. I've had two thermistors do exactly that. It is a common problem with 1st gens.

My solution was to remove the thermistor and epoxy/JB Weld the sensors back onto the unit's frame. It worked great.
 

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Not sure what tests were performed, but it is common for the fuel level thermistor to crap out, uncommon for the gauge electronics to fail.

If you haven't already, you can try to artificially activate the low fuel light by grounding the R/B gauge wire, and/or activate the very low fuel light by grounding the B/Lg gauge wire.
Hi Guys, I hope bumping a thread this old isn't bad form. This seems to be a pretty common curvy problem so I'm sure more newbies like me will appreciate the added input.

I'm having a no fuel indicator light problem, and the light doesn't come on when the key is in the "ON" position, making me think there's a gauge problem. I'd like to test by grounding these wires as described above, but I'm unclear on the best spot to do so. Is it a matter of jumping two pins on a connector under the tank? Disconnecting wires from behind the cluster?

Did a full bottom-end rebuild/restore on a Ninja 250 a couple summers back so electrics and mechanicals aren't completely foreign to me, just the SV! Thanks for reading.
 

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...I'd like to test by grounding these wires as described above, but I'm unclear on the best spot to do so. Is it a matter of jumping two pins on a connector under the tank? Disconnecting wires from behind the cluster?
Any place you can access Black/LightGreen(empty), and/or Red/Black(low) is OK. Obvious locations are directly at the fuel pump connector, or at the gauge cluster.

If you ground the wires at the gauge connector, the plug must be installed while testing else the gauge won't see the signal. If you test here, the wires can be tapped by pushing a pin through the insulation then clip a jumper lead between selected pin and gnd (black/white).

If you test at the fuel pump connector, the plug may be removed while testing, just jump the appropriate pin to gnd. You may also just back-probe the connector.

It may help to know WHY this works: The bulb in the gauge has constant 12v on one side, the other side goes to the fuel thermistor. When the fuel thermistor is covered in fuel, it is high resistance (no connection, no light); when uncovered, it heats up it goes low resistance (makes a connection to ground), thereby lighting the bulb. Jumping the thermistor wire to gnd emulates an uncovered thermistor and should light the bulb is all else is OK.
 

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oops, you are correct, RMAN, gen1 not gen2. Option, can test at the thermistor under the tank, gen1.
 

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Thanks for the clarification guys! Yes, it's a gen 1 so I'm probably going with the "pin tap" at the gauge cluster approach. (Though I'll also take a look under the tank to see how accessible grounding the thermistor lead is.)
 
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