approx fuel left when light comes on???

I would not count on 9 gallons when the low fuel light comes on.

Maybe the chassis owner's manual will list that information? My motorhome is old enough that it doesn't have a low fuel light, just the usual gauge.

My car owner's manual states that the light comes on when there is "approximately 1.62 gallons left" in the tank, which always struck me as a rather oddly precise approximation. Perhaps it varies by a few tablespoons or something. I should perhaps note that the tank holds a total of about 10-11 gallons, and the car gets nearly 40 miles per gallon, so 1.62 gallons is a reasonable amount of warning before running out on that vehicle.

What I would do is just go with what you figured out already... Your low fuel light comes on when you have ~ 9 gallons of gas left... Done deal. :)

When my low fuel light comes on, I have about 5 gallons left, but that's with an F150 with the 36 gallon tank.

However, if I have 1/4 tank left (~9 gallons) and I park on any kind of slope with the nose of the truck down, it'll throw the low fuel light.

I now don't let it get past 1/4 tank if I can help it. If I have to go more, I know that I've got at least that ~ 5 gallons once the light comes on and I'm looking for gas ASAP..

Good luck!

Mitch

I don't like to push my luck so make every attempt to stay out of that zone. It has come on a few times but I haven't been bitten..... yet.

To many variables. I fill up at or before 1/4 tank.If you start looking at 1/2 you won't be in a rush to find "someplace" before it runs out.
Bill

I think a lot of people would like to know that magic number. Sounds to me you go it about right. With a 55 gallon tank you can be a couple gallons either way depending which way your truck is leaning front to back or side to side when you fill up. But I bet you are close. JMHO