Fuel gauge accuracy

[Guest]

1981 GS650GL, completely stock.

I refurbished the tank and fuel sender unit while restoring the bike. The sender unit works but I'm concerned about the accuracy. I drove about 107km and the fuel gauge indicated less than 1/4 tank remaining. When I filled up it took just over 7 litres. The tank holds almost 16 litres so the gauge is obviously way off. Is there any way to calibrate these things or are they just this inaccurate? Or could I have installed incorrectly? Maybe it's rotated one way or the other by one screw?

[tkent02]

You can calibrate them to be very accurate.

[Guest]

The gauge on my 750 is pretty close, when it says half a tank, it will take about 2.1 gallons, at 1/4 of a tank, usually about 2.8 give or take. That's at hiway speeds of around 75 or so

[Grimly]

My needle moves off the stop - I've got some fuel.
Good as it gets for now.
It used to be more accurate and I might do something about reclaiming its accuracy, but I suspect I'll probably have replace the sender.

[chuck hahn]

What I do is to take half of what the service manual says is tank capacity and put it in the tank. For example if it says 5 gallons I put in 2 1/2 gallons ( I use the gas pump as my gauge and fill a gas can ). Turn the key on and wait a good 2 minutes to be sure reading is as settled as its gonna get.

If the gauge reads low of the half tank mark, you bend the float arm down a little. If it reads higher than half you bend it up. Reinstall the unit and out the gas back min and repeat the process till you re happy with where the needles finally settles.

[Grimly]

What I do is to take half of what the service manual says is tank capacity and put it in the tank. For example if it says 5 gallons I put in 2 1/2 gallons ( I use the gas pump as my gauge and fill a gas can ). Turn the key on and wait a good 2 minutes to be sure reading is as settled as its gonna get.

If the gauge reads low of the half tank mark, you bend the float arm down a little. If it reads higher than half you bend it up. Reinstall the unit and out the gas back min and repeat the process till you re happy with where the needles finally settles.

Useful info, thanks.

[Steve]

I also calibrate a gauge when I get a bike. Similar to what Chuck Hahn does, but I do it at the REServe point, not half a tank. I will empty the tank into an external can with the petcock in the RUN position and note the gauge position when the flow stops. Bend it as Chuck said to improve your accuracy.

Personally, I don't care if the gauge stays on FULL for the first 75 miles then starts dropping like a rock, but when it gets to that transition from the white line on the gauge to the red line, I KNOW I will be reaching for REServe soon.

It also follows the level once you are on REServe, letting you know when you are almost EMPTY.

.

[chuck hahn]

I like them to be pretty close also Steve. Like you said, when the edge of the redline is at the needle I got about 1 gallon left till reserve is hit. I think of it more as an indicator rather than a precision gauge...LOL

[Guest]

You can calibrate them to be very accurate.

how do you calibrate? interesting thread.

[srg]

You damn kids are so spoiled with your fuel gauges. I open the fuel cap and use a lighter to look inside the tank to see how much fuel I have.

Note: For anyone reading this who thinks I'm serious: I'm not.

[Guest]

You damn kids are so spoiled with your fuel gauges. I open the fuel cap and use a lighter to look inside the tank to see how much fuel I have.

Note: For anyone reading this who thinks I'm serious: I'm not.

I don't carry a lighter Though I do have a 2100 lume tactical flashlight in my bag...that would be like sticking the sun in your tank huh.

[tkent02]

Whatever happened to felling the sides of tank as you ride? This ain't rocket science. At least it shouldn't be.

[Guest]

Whatever happened to felling the sides of tank as you ride? This ain't rocket science. At least it shouldn't be.

That works great on a propane tank, I've tried that a few times on my bike, just not that much of a difference. One would think because of the heat in this area you could feel a good difference, I couldn't. One I did on my fuel gauge was to extend the red line a bit lol.

[tkent02]

It's what I've been doing for decades, give it a little slap, you can tell even with gloves on.

[JEEPRUSTY]

Chuck how are you bending the arm? Are your removing the sending unit from the tank each time?