Fuel tank sender mystery...

[alexis291]

Hello, despite checking existing threads on this topic I haven't found one with these same symptoms yet.

Since I bought my 1995 k1100rs the fuel gauge has been erratic but spends most of its time showing full, whatever the tank level. I fiddled with the connector on the sender (behind the tank) and the gauge worked for a few days (hurrah!) then went back to its old tricks. D'oh!

I have taken the sender unit out of the tank, checked the track visually and that the wiper is in good contact. Cleaned both with wet & dry and in fresh air it worked fine. As I moved the float arm up and down the gauge did just what is supposed to. However, back in the tank with fuel in, the gauge just sits on full, whatever I do with the float.

Can any genius suggest something else I can try before putting my hand in my pocket and buying a new sender?

Thanks

 PS-The fuel low-level light has always worked ok.

[rbm]

Your problem most likely resides in the gauge and not the sender.  The gauge shows full when its input is grounded, so there might be an intermittent short inside the gauge or there might be a bad connection in the wiring from the sender to the gauge.

1) If you have the time, follow these instructions for testing the sender.
2) check and clean the gauge connections

As a last resort, if these steps don't solve the problem, is to open the gauge and inspect it for loose or bent wires that might touch the outside of the case.

The low fuel level light continues to function because it is connected to a completely separate circuit on the sender than the one which records fuel level.

[alexis291]

Thanks, good informative article you linked to.
Although I cleaned the contacts and track I didn't clean the pivot point etc but I can test this with an ohm meter. Then check the gauge as you suggest.
Thanks again.

[alexis291]

Well the update is that my gauge is now working but I'm not quite sure why... I do think it was the gauge itself though. What I did was start to dismantle the gauge by dissembling the wiring on the back. I got to the point where I realised that the casing appears to be pressed together and I would have to start being destructive to get it apart so I stopped. When I put the wiring back on, it worked and has done since. So the fault is fixed but I'm not 100% sure what it was, which is not entirely satisfactory!

[rbm]

I just recalled that I had a similar problem with the gauges on my old K100.  The issue was the connector on the gauge.  It was very corroded and did not offer a good contact.  I had to reseat the connector several times to correct a defective reading.  I would recommend thoroughly cleaning the gauge connectors, if you haven't already done so.