The wiring diagram won't tell you much. The spark is controlled by the ecu, and these ecu's have a tendency to have failed capacitors, which leak and eat up the board traces. One of the first signs is a loss of spark (and without spark, the injectors dont fire either). Remove the ecu and smell for a fishy smell.

Test for 12v+ at the coil plus terminal (wiring diagram with connector diagrams is necessary here). Test for same at coil - terminal. Test for spark at the coil wire while cranking. Test for varying 12v+ at coil - while cranking, should flicker as the ecu breaks the coil ground to produce spark. Using jumper wires, connect coil + to batt +, and connect coil - to ground. Holding coil spark wire 1/4" from a good ground, make/break the coil - to ground path and see if you get spark.