[ischmitz]

At this point fuel pressure can build up during cranking. That more or less gives your DME relay a clean bill of health. While it might make sense to carry a spare (they do fail quite a bit) it will not solve this issue.

Next you need to determine if only spark is missing or all DME signals (fuel pulses, spark and tachometer). Some observe the tachometer during cranking which is the third signal that indicates the DME goes into RUN mode when it "sees" flywheel motion with both sensors. Or get an LED test light or a NOID light kit to visualize fuel pulses on the injectors while cranking.

If all three signals are absent it likely points towards the flywheel sensors or in some rare cases a defect inside the DME with the sensor amplifier. Insulation of the FW sensors cracks and ages, humidity gets into the COAX and the signal deteriorates. Time to check them (measure AC voltage during crank, check for shorts or get a cheap oscilloscope to measure their outputs) or straight replace them.

If only spark is missing this points to a failure inside the DME. Either solder joints or the driver or driver conditioning circuit are bad and the DME needs repair.

Keep us posted on findings