I wouldn’t say it’s “merely a voltmeter.” If it were, the damn gauge would be bouncing all the time as the gas sloshes around inside the tank.
I’m not sure what they’re doing on modern cars, but on most older cars the fuel gauge is actually a temperature gauge heated by one or two bimetallic elements (also located in the gauge). The gauge is thus measuring the rms value of the current. The time constant of the heater/bimetallic strip is designed to be fairly long, thus filtering out the short-term current variances caused by sloshing fuel. (There was also another system that used two coils 90 degrees apart, but I’m not sure how common it was.)
**Well I’ve finally done it: 1000 posts. So do I get a prize or what? **
Oh the hell with the fuel gauge!
My ancient '86 Ranger quit telling me how much fuel remains. My solution? Fill it up (completely) every time I refuel. Do the math to check mpg using the trip odometer to determine when’s an appropriate mileage to refuel again. Heck of a lot cheaper than replacing the sensor.
I’ve ogto a 1989 Honda minivan that has a completly useless fuel guage. I, too, go by the odomotere. In reality, since my driving is so regular, I go on a 23-mile trip twice a day six days a week, I don’t need to worry. OI don’t drive much beyond that, although on weekends, I might do an extra day’s worth. That’s… what… 7225 is around 350… hmm. Perhaps my estimate of the trip distance iks off.
My fuel tank lasts around 325 miles, so I just refill on every Thursday, when the lines are shortest.