It is weird because in my 1991 Honda Accord after I fill it to the top it will drop like normal to 3/4 and I will have about 90 driven but the next time I start it, it will be just above 1/2 full with the same 90 miles. It seems like i am only getting 250 Miles Per Tank. What could be the problem.

 

THIS IS NOT HOW YOU CALCULATE MILES PER GALLON!!!

Try again with using actually figures. Fill up your tank all the way without topping off and reset the trip meter. Drive the car until it is around 1/4 left on the gauge. Fill all the way back up to the top and divide the miles on your trip meter by the gallons you put in. Do that several fill-ups and get a rough average of what your actual MPG is. Do not guesstimate, do not use miles per tank, do not do anything remotely like that.

There are also 300 threads regarding this very same topic, some of which are quite recent. How about searching and going through them for some suggestions, fixes, etc?

 

Do you notice a gas smell anywhere near your car? What you described makes me think you have a gas leak somewhere.