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Malfunctioning Fuel Gauge

Retired At LAst

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Retired At LAst

After some 103,000 miles my rtps fuel gauge is malfunctioning. No matter how full or empty the tank is it shows full/all bars.


Any simple fixes without having to remove the tank?


Luckily I know range, as I consistently get 42MPG.

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Does your low fuel light work? I assume the RT-P is the same as the RT, but I'm just assuming there. On the regular R1100RT the low fuel light is actuated by a float on an arm, and the fuel gauge is actuated by a float in a very thin-walled tube - both of these are within the tank. A common fault is for vacuum to build in the tank - often from a blocked emissions line - and cause the tube to deform so the float gets stuck somewhere. Mine, for instance, is deformed in the middle, so the float will only go down to about half a tank (so I always have plenty of gas ;) ).


Fix for that involves pulling the tube and either carefully reforming it or replacing it. I'm waiting until my next fuel filter change to do that.


I'm sure there are other possible faults for the display - someone smarter will tell you how to know what you have.



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Morning Retired At LAst


Does the "always full" change with just the key ON but engine not running? If so suspect a fuel pump pass through grounding issue. There was a BMW service bulletin on adding a supplemental ground to the fuel pump pass through area.


If it doesn't change from key ON to engine running then suspect an open in the fuel gauge wire between fuel tank & dash, or open in the fuel gauge ground inside the tank (somewhat common on older bikes) or possibly an issue with the pass through connector ground being open (again somewhat common).


About all you can do is remove the tupperware & check the wiring & ground form the sender tube all the way to the dash.


As szurszewski suggested it could be a crushed fuel sender tube but as rule that doesn't give a "full all the time" condition. That usually results in a partial full reading that doesn't change or a reading that only moves a little.


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Galactic Greyhound

I have a Word document on R1100RT RID (Rider Information Display) testing which also includes the Fuel Plate wiring.


The file is too large to post here - if anyone wants it then contact me with your email address and I will send it to you.


I wrote this when repairing faulty Fuel Gauge and Oil Temp gauges on my 1996 R1100RT.

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