Can you actually get a measuement of the tank. There is a formula for figuring out gallonage in a tank.

Tank ( Gallon Volume ) Formula

Thanks for this Cam. I might be able to find the dimensions on the paperwork that he passed on to me when he purchased the tank...

Maybe I missed it, but is your tank guage a mechanical one? The trick would be to figure out which guage is correct (if either) it's pretty easy to make some adjustment by just bending the float arm on the sending unit.
Otherwise do some math & figure out what it really indicates & just compensate.

I used to have a mechanical & an electrical guage & I still ran out of gas 'cause I trusted them too much, they were both broken!

Now I make sure I have plenty & I top off the tank to make sure.

Doug

Doesn't matter how much the tank holds, just the depth of the tank.

Can't you just remove the sending unit with wire still connected
(You need to connect a jumper to ground to get a complete circuit)
, measure the depth of the tank with a ruler, check the swing of the float to see where it gives a full and empty reading, adjust the length of the float arm so that the range corresponds to the tank depth, put it back together?


Sending unit reading is linear. Square/rectangular tank volumes will read correctly.
If its a belly tank it will not be linear because there is more volume in the top half of the tank than in the bottom.