The fuel gauge is a very simple electromechanical design that basically uses a float and rod to operate a variable resistor. That resistor controls the amount of current that flows through the actual gauge, and the amount of current is directly proportional to the deflection of the gauge needle (or the number of lit LED segments in that sort of gauge). If we assume the gauge itself is OK (it can be easily tested with the Harley tester all dealers should have), then we need to make sure the float and rod are properly adjusted to provide the correct resistance for the gauge.
In my case the gauge was reading much higher than it should have, and the fix was to either bend the float rod or just add a resistor to the circuit to lower the gauge reading. I've done these sorts of adjustments both ways, but in the case of the SEEG it was easiest to just add a variable resistor to the circuit and adjust it until the gauge read the way I wanted it to read. If you have the opposite problem and the gauge reads lower than actual, you only have the option of bending the float rod. It's a more complicated fix that requires you to remove the fuel pump and sending unit assembly from the tank, then bend the float rod (trial and error), then retest to make sure you bent the rod the right way and the correct amount. I didn't say it was easy, and it sometimes takes a few attempts to get it right, but once it's adjusted correctly it should be very repeatable. Mine definitely is.
BTW, when tweaking the gauge it makes sense to adjust it for an accurate reading at the low end of the scale, not the top end. You really don't care if the tank is 3/4 or 7/8 full, the important part is if it's 1/4 or 1/8 full. I was able to make mine accurate at 1/2, 1/4, and E, but it reads about 7/8 when the tank is actually full.
The sad part of all of this is the fact that I haven't owned an automobile in decades that had a seriously inaccurate fuel gauge, and the most recent vehicles I've owned have been very accurate at all levels from Full to Empty. The wife's current ride is Full at 20 gallons, 3/4 takes 5 gallons to fill, 1/2 takes 10 gallons to fill, 1/4 takes 15 gallons to fill, etc. If the auto industry can use the same technology (electromechanical gauge system with a float and resistor in the tank) and come up with very accurate and repeatable gauges, there is no reason Harley couldn't do the same. But they might have to spend a couple bucks on the components, and design the sending units so they weren't so easy to knock out of adjustment during installation. Harley isn't real big on worrying about inaccurate gauges or a whole lot of other things that irritate their customers, unlike the much more competitive auto industry. People with cars that run out of gas while the gauge still registers a quarter tank tend to raise hell and even sue. People with lousy gauges on their Harley usually accept the BS from the dealer about it being normal and then let people talk them into using the old outdated trip odometer method, which is no better than a bad gauge IMHO. And all this "settling for junk" is what allows Harley to continue to successfully peddle junk, IMHO.
Jerry
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Topic: Low fuel light? (Read 4215 times)