wacky fuel/gas gauge/gas tank capacity when topping off?
 

I've been puzzled for the last year by occasionally large gas bills when I top off my R52.

Usually, it happens like this: I see the gas gauge is at some particular mark, say 3/4 full. I drop in the gas station to top it off and put the nozzle on automatic till it cuts off. When I see the receipt, it says that some unexpectedly high amount of gas has been pumped, such as 6.5gal. The gas gauge is totally full, past the 100% mark by about 1/8in (the maximum position of the gauge).

Based on simple calculations, if 0.3 of a tank is 6.5gal, then the tank's capacity is a whopping 21.6gal! But the R52's user manual clearly states that the tank capacity is just over 13gal (IIRC, it is 13.2gal).

Now, this doesn't happen every time I go and top the tank off. Sometimes the number is reasonable, such as 1/4 tank = 3gal.

What's going on? I don't think my gas gauge or float is broken--the gauge says the tank is full when the tank is full, and it doesn't jump around or get stuck at any value.

But I obviously don't have a 21gal tank!

Anyone else experiencing this sort of wackiness? If so, what was/is the fix?

Thanks in advance for your help!

The gas gauge is not linear, and very inaccurate.

Three fourths of a tank may be more like half a tank.

On my Gen1 I always use the trip meter. Reset at each fill up and then refill at 250 miles, this routinely results in around 12 gallons. However I only get about 22 mpg.

There are threads on this forum discussing in more detail.

As long as the red light goes on before your empty your good, mine didn't there for awhile...

Ah, I see, thanks. One question: is it possible for the gas gauge to lie and say I have plenty of gas when in reality I am running on fumes, about to get stranded on the side of the road?

It would seem that it could, if it could lie and say I have 3/4 of a tank when in reality I have 1/2...