That problem is usually the sending unit in the tank. Have someone make sure all the grounds are clean and tight. They are enclosed in plug in connectors, and will be loos internally. They sometimes can be tightened with a thin utensil. However, the most important connector is in the tank. The fuel sending unit and fuel pump are one unit. Personally, my advise would be to keep track of the miles you go and when you approach max miles, fill it to the top. Lacking that, be prepared for a fairly large bill. You can wait until the fuel pump quits and make sure they check those other grounds, also at the same time. If you habitually run below 1/4 tank, you will certainly need a fuel pump assembly sooner rather than later.