Dying fuel gauge

[Danie.e]

Interesting phenomenon - When I start my GS1000G it purrs like a kitten and all is well. When I mount the beast and start riding, the fuel gauge acts weird. On idle it gives the "actual" level of the fuel in the tank but as the speed increases the needle slowly moves to empty. When I release the throttle, the needle moves up again.
My battery does not go flat, charging system works as it should, and everything else is OK. Any Thoughts?

Thanks, Danie

[Rich82GS750TZ]

On acceleration, fuel is sloshing to the back of the tank, needle dips. On deceleration, fuel sloshes forward, needle rises. All due to the float in the tank. Same happens on inclines. Needle will only settle when riding oat a constant speed/pitch. Battery strength has nothing to do with it, unless it’s dead, then nothing works.

How accurate your gauge is depends on the bend in the float arm inside the tank. It’s good to know where your gauge reads when you need to switch to reserve/fill up

[2BRacing]

Interesting phenomenon - When I start my GS1000G it purrs like a kitten and all is well. When I mount the beast and start riding, the fuel gauge acts weird. On idle it gives the "actual" level of the fuel in the tank but as the speed increases the needle slowly moves to empty. When I release the throttle, the needle moves up again.
My battery does not go flat, charging system works as it should, and everything else is OK. Any Thoughts?

Thanks, Danie

I think it has something to do with the voltage stabiliser circuit attached to the fuel gauge. The gauge has bimetal controls for temperature and voltage stabilisation. At idle, your charging system voltage output is low and the gauge reads correctly.

As revs increase, charging system output voltage increases, and the voltage stabiliser bimetal "overcompensates" and opens the circuit, causing the gauge needle to move towards empty. When revs decrease, charging voltage drops, and the voltage stabiliser bimetal makes contact again, restoring power to the circuit and the gauge needle rises again. Unfortunately I have no idea how one would fix such an issue, if that is indeed the cause of your gauge's movements.

I have never seen the gauge needle on my bikes moving as a result of fuel sloshing due to acceleration / deceleration. Do you have the OEM workshop manual, which has tests for the float portion and gauge portion?

[Brendan W]

Sounds electrical. If less current is going through the gauge it will head towards E.
Is it possible that the charging voltage is falling off at higher revs?

[Grimly]

Used to be, on some small cheap European cars, you would see the fuel gauge rising and falling with vehicle movement. That was caused by an electrically un-damped fuel sensor. The electrical damper is a simple device and fairly universal on most 12v car and bike systems. I thought I had a defective one, but it was just bad connections, so I never actually identified exactly where the damper is on the 850. It's hiding there somewhere though.

[Danie.e]

Thanks for the replies, much appreciated. This happens even if I am stationary. Charging circuit is healthy - as throttle is opened, the headlamp burns brighter. Measurements correspond with Suzuki specs. Guess it must be the voltage stabilizer circuit. I do have another set of clocks and will swap them out just to see if it makes a difference. Will report back here.

[2BRacing]

……. I thought I had a defective one, but it was just bad connections, so I never actually identified exactly where the damper is on the 850. It's hiding there somewhere though.

The voltage stabiliser for the fuel gauge is a bimetal strip mounted onto the back of fuel gauge itself. A second bimetal strip linked to the pointer of the fuel gauge handles the signal from the float.

[Danie.e]

Did all the work to change clocks only to find that the fuel gauge does not work at all. At this point in time I tend to agree with all that the "voltage regulator" is faulty and will ignore the issue for now until I find a nice set of clocks to replace the one I have. Thanks a lot for the info and feedback.

[2BRacing]

Ah no, that's very bad luck! I have not looked at a set of clocks closely, so not sure after taking the shiny cover off the back, if you can get into the "guts" of the fuel gauge? There may just be a wire loose on the spare set.

[Rich82GS750TZ]

I'm sticking w/ my story. I do not experience any fluctuation in the fuel gauge when revving at a standstill. I do notice the needle move smoothly on acceleration/deceleration, and on going up/down hills. I did not experience any noticeable brightening of the headlamp with revs, even before switching to a LED TruckLite. I'm not saying it's not a voltage stabilizer issue, just that I have no reason to believe that that's what I see when my fuel gauge needle moves while riding. I'm a dummy with the electrics, so I absolutely rely on people here to steer me right, and I'm not above admitting if I'm all wet on this issue. I am definitely interested to find the results of any testing. This is the first I've read anything about such a voltage stabilizer.