Why wont my 1993 nissan pickup start?

Check the positive cable going to the start and the negative cable going to the ground,are the cable tight at the battery.

Could be this,test it if you can to make sure.

sounds like you have a ground problem . Do you have a wire from your battery post to your frame anywhere. good luck

I would take a real close look at the battery cables. Make sure the battery posts are real clean and the cable clamps. You can use a paste made of baking soda and water to clean any corrosion, and then a fine sandpaper ( like 180 grit) to clean the posts and cable ends. then check all lyour connections, make sure they are clean and secure.

There are a few thing that can cause this problem. Not knowing what engine you have all I can give you is generic things to check. Fuel filter, make sure it flows well; spark plugs, make sure they are in good shape; air filter, make sure it is in good shape. Beyond that I need the engine to go deeper into it.

HAS TO BE BATTERY CABLES.IF CABLES ARE OLD REPLACE THEM PROBABLY YOU GETTING POOR GROUND AT NEGATIVE BATTERY CABLE.IF BATTERY CABLES CLEAN FROM CORROSION GOOD TIGHT.CHECK STARTER FUSE OR RELAY.IF ALL IS GOOD HAVE STARTER CHECKED OUT AT AUTO PARTS STORE AUTO ZONE.

there are 4 wires go to alternator
2 white wires go to battery
1 black wire goes to ground
1 yellow/black goes to bulb check relay
starter has only two wires
the big one goes to the battery and the small one goes to ignition system. you can not mix the terminals because the size of the studs on the starter

It goes:

Tan/white (wire closest to the spark plug)
Purple/white
black/red
tan/black (furthest from the spark plug)

In caburator, check fuel needle valve not ****, or chect to see if you have water is floating on main fuel bowl caburator jets .Clean in general.

Those wires need to be replaced or repaired. They probably were rubbing together and shorted out, not uncommon in older vehicles. If you do it yourself, make sure you replace them with the same gauge (size) wire and use heat shrink tube on your joints. Do them one at a time so you get them hooked up right.
Once you get them repaired you may find other electrical problems that have occured because of it, it all depends on where they went.Hope this helps.