Depends what the symptoms are, but I'll assume won't run, no fuel. My 1986 Trooper 2.3 gas came with a mechanical fuel pump, located under the intake manifold. I would start by looking at the front of the carb, there is a glass letting you see into the float bowl. If you can't tell if there's fuel, try pulling the fuel line off the carb , sticking it in a can, and safely cranking the engine to see if you are getting fuel. No fuel? There is a fuel filter underneath the vehicle, just ahead of the RR tire, inboard of the frame. Check that.