I have a 2000 mercury grand marquis 8 cylinder it ran out of gas and now it will not start. after it put gassed the car up gas is getting to the motor but still will not crank and it did backfire once

SOURCE: 1993 Mercury Grand Marquis

starter cylinoid

SOURCE: Backfiring under the hood while I'm driving on my 1992 mercury

sparkplugs

SOURCE: where are the spark plugs located on a 2000 Mercury Grand Marquis

There are eight COPs (coil-on-plugs) to remove. Using a 7mm or 9/32" socket, remove each bolt securing each COP to the intake manifold on top of the engine. Remove all eight COPs, and the spark plugs are underneath. When replacing the spark plugs, use only the proper Ford/Motorcraft plugs, even if they cost twice as much as the aftermarket ones. You will avoid further headaches this way. Hope this helps.

SOURCE: #8 fuse blows as soon as replaced

First and the easiest problem area are the sun visors. These have an integral vanity mirror and light powered off fuse #8.
Lowering and raising the visor chaffs the power feed wire until it shorts on the mounting point and blows the fuse.
If you look at the metal mount with the 3 screws you can just see the wire, you might also just be able to see the worn insulation.