Again as I said above what you are describing is what you have set it to do and the wait time is indeed being updated. I think what you're looking to do is set the wait time to fuel max, fair enough that'll be the entire time it takes for the fuel to disappear, then you probably want to also set fade out time to fuel max, instead of 1 second? If you run it in debug mode you can see that the wait time is 5 (fuel max)