Low, you are referring to same data - it doesn't matter if the comp says 80 or 350 miles, it is not reliable. It is like x+y=10... We can't determine x nor y - insufficient data... You need to do other calculations as suggested by very experienced folks in order to determine the root cause of your issue...

Next time when you are empty, fill up, tell us how many gallons you got and what mileage was reported, and if possible, what was in the saddle tank...