cant get it to crank

Sounds like the diagram in the fuel pump has failed, The carbureted engines all use a mechanical fuel pump located on the right side of the engine. The pump is a diaphragm type pump and is actuated by a rocker arm through a link and pull rod. If the carburetor isn't getting fuel the fuel pump is the next thing to replace

you say your truck is a 1989 i think that is should be a throttle body? if it is you may have the two gas line switched up one should be in and the other a flow back which will go back to the tank hope this helped