Front gas tank size on a 1994 f150 xlt 4x4 truck

Your local parts Haus should be able to answer most of your questions. The front tank is side mounted and I believe it is a 15 gallon tank. Look on you tube for help in removal and installation. Then, first of all, do you feel qualified to do the work? Sometimes the truck bed itself is removed which makes the work a lot easier. If you elect to work from beneath the truck, then be prepared for a little more awkward work. You will have to block up the tank before releasing the two straps holding the tank in place. Next you will have to disconnect all wiring to the in- tank fuel pump, along with the fuel lines (which will require a special disconnect tool). Also, the filler hose will have to be loosened and removed. Finally, after all this, I think it would be wise to also replace the in-tank fuel pump since it will be very accessible at this time. Then it is time to put it all back together. Believe I would also add Seafoam when filling the tank. Not knowing your abilities or circumstances this could turn into a tough project. If you can afford it you might be better off taking it to a reputable garage. Wish you well.