My low fuel light has never worked. Does anyone know the colours for the fuel gauge on the tank plug and the colours at the Instrument panel.

I wanna stick my paw in the tank and wiggle the float to see resistance change at the tank plug and then buzz that through to the instrument panel plugs to isolate the fault.

I thought I nailed it last time I opened the panel and saw the bulb wasn't connected, but no, not that easy

clean up the tank connector pins before you do anything

those sockets in the female part of the plug tends to open up letting corrosion occur in there

had a similar issue ...

crimped the sockets slightly after a clean up with deoxit .....all good

It's in about 3 millions bits Charlie
I thought I could fault find while it's apart.

there have been a few post about the senders in the forum over time including good pics of the assembly out of the tank ....worth a look

the pin on the armature to the float arm has been noted to bend ...and might explain a few things

i think its either the brown white or brown black that are the cables for the sender stuff .....not sure which one is which at the moment (old person issue )...

Cheers, that'll get me started on it.

I did search but putting fuel in the criteria brings back lots of hits on the pump.

I'm not sure.....do you have an actual float sender in the tank or the older set up for warning light(s) only?????
It may very well be normal that one of the 2 openings in the speedo board for the fuel lights is vacant. Should be a bild in the one closest to the center for 4L light.
left side 7L light is disabled on most.
I'm not sure which sender yours has but most have 4 wires I think??? 2 for the pump.....the other 2 for the lights?

Yes it's a float sender, there are 4 wires on the tank plug. I just wanna stick my fluke into the plug to see resistance change as I move the float and then buzz the wires to the panel to see where the issue is. It all been detoxed already.

I also received a chinese fuel gauge this arvo. It has VDO on the dial but I'm sure it's a knockoff. If all else fails I'll make this gauge work and install it in the fairing.

I'm really not versed in the 86 & later float assy.
seems like you could use the ohm meter to just trial & error the various connections at the bottom of the tank (no vehicle power connected).
If you disconnect at least 1 wire from the fuel pump, then the 2 of 4 wires to the pump should check completely open.
I'm not sure, but I'm guessing that the other 2 wires, 1 might be for the gauge and the other would be the light?????
If so, one of those 2 wires when connected through the ohm meter to the metal of the tank might be smoothly variable when moving the float from top to bottom & back, The other of those wires should be open at the top and be low or no resistance when it gets to a point somewhere near the bottom when it trips the micro switch in the float.
That's all a guess......other members will have to correct/verify the information.
I'm guessing further that the 86 has a light only but no original gauge?
If so then the float only uses the resistance of the float "wiper" circuit to vary the resistance to the fuel light control board in the speedo? Someone here will know.
Sorry I could not provide more definitive help on this one......but I will learn as you do

Low fuel light is on White, Gauge conection is Yellow and pump is Green/White. Brown is earth and is a common earth for all 3 circuits.
The low fuel light and fuel level gauge don't work off the same wire, they are totaly seperate circuits.

Cheers Rick, both are working from the tank but the float has to be a long way down before it triggers.
I might completely empty the tank and measure it back in to see where it's triggering.

I haven't followed this thread as closely as could be, but if the bike is ride able, now that you have determined that the light will come on......you could fill the tank and set the trip odo.....drive about 225k or a few more and that's about where the tank should have around 4L left. If you get to 260K it may be time to check the level in relation to when it comes on by manually moving the float? I think you can comfortably go 280K or more before running out.
What do the other members think Kilos wise?????
regards, ibj...

I used to get 320 -330km to dead empty on the K100 and that would take 19.8 lts to full but the K1100 gets 370 to the tank.
I also use a 10mm high ring under the cap to lift the cap and I can get an extra 1.5 lts in on top of the normal fill

ibjman wrote: I haven't followed this thread as closely as could be, but if the bike is ride able,

No it's in a million pieces, the last guy said it didn't work and was refuelling at 350 Kms but I found the bulb wasn't connected in the panel so it probably will work now. But this eBay gauge works, it is backward, so it reads 3/4 full at dead empty with 110 ohms coming from the float. I found the plug in the loom where the gauge pops out so I'll just series in a resistor so it reads full at dead empty and install it upside down

Not sure how those should work....never had one with a float.
General services with a fuel gauge is that with the power on the dash gauge, if you ground the other side of the gauge it should go to dead empty. If you remove the wire from ground it should go way past full. Not sure if the bike works the same way.
Any chance the PO of the part has just the float arm installed 180 deg. out on the sender?
I have my own issues going on with early fuel warning light(s).
Always Good chatting with u

The k100 float is reverse of the normal float, hi ohms at empty and lo ohms at full. The BMW gauges work correctly.

I found the dash light wire goes low at just under 4 litres. I left the fuel level low to trigger it, so I should see the fuel light on the dash when/if it all goes back together

sound about right ....good luck when it gets rebuilt