Why your 1986 Buick lesabre is not taking the 18 gallon of gas?

Your 1986 Buick LeSabre may not be taking 18 gallons of gas due to several potential issues. First, check for a clogged fuel line or filter, which can restrict fuel flow. Additionally, the fuel tank vent might be blocked, causing pressure buildup that prevents proper filling. Lastly, ensure that the fuel gauge and filler neck are functioning correctly, as they could be providing inaccurate readings.