Fuse keeps blowing?

You didn't include any information as to which fuse, which circuit is affected, is this intermittent or does a new fuse blow right away, etc. With nothing to go on, I can offer a trick that will prevent you from wasting a lot of fuses in a futile attempt at solving this. It involves replacing the blown fuse with a light bulb. When the short is present and the circuit is turned on, the bulb will be full, normal brightness, and hot, so be careful to not lay it against anything that will melt or burn. When you do something to eliminate or isolate the short, the bulb will become dimmer or go out. That bulb will also limit current in that circuit to a safe level to protect the wiring.

The items needed are shown in the third drawing. I drew a common 3157 brake light bulb. That limits current to one amp. With such a small bulb, once the short is gone, the circuit will resume trying to work, but the bulb is going to prevent normal operation. If you want to, you can substitute a head light bulb for this procedure. Those will allow up to five to six amps of current flow. That is plenty to allow lights to light up enough to see them working, or for a motor to run slowly.

The easiest way to connect the bulb is with a pair of clip leads and a pair of generic, universal spade-type terminals. You can find a dozen clip leads for about three dollars at Harbor Freight Tools. These are available in different sizes. Stick with the smallest ones to insure the alligator clip will fit inside the terminal.

To buy the terminals, you'll end up buying a box of typically 50 or more. Instead, any electronic hobbyist will have many of these lying around. The spade end should be no fatter than the terminals on the fuse. It's common for the wire end to be too small in diameter for the alligator clip to fit in. The blue terminal has the insulating barrel removed by twisting it off. Now just stick the terminals in that way, and clip the alligator clips to them. The fourth drawing shows the terminals inserted in the fuse box terminals. In the fifth drawing, a clip lead has been connected to each terminal, and in the sixth drawing the light bulb has been added.

If the test bulb is dim or off, you'll need to do something to make the short occur. That can include opening and closing doors, tapping on the body with a rubber hammer, and wiggling wiring harnesses. When the bulb flashes full brightness, you're in the area of the short. Look for wiring harnesses that fell down onto hot exhaust or engine parts, and for a harness that is draped over the sharp edge of a metal bracket.

If the short is constant with the bulb always at full brightness, a better approach is to unplug various connectors and items until the short goes away, Once we know which circuit you're working in, I can post the appropriate diagrams and suggest places to look for the short.