GMC Repair: GMC safari 1988, gmc safari, gasoline engine

Question
Vehicle is on propane but wont start it worked the day before but in the morning i went out and the started goes but no spark. Replaced the coil still nothing did the screwdriver test on the coil wire no spark coming from coil. Any ideas?  

Answer
Hi
First I will answer this as if it were a gasoline engine as I have no reference for a CNG vehicle.
Check for power to the coil on the pink wire.
If not check fuses and fusible links.
If so make sure you getting power to the Ignition module, located under distributor cap (again, on pink wire).
If so suspect the ignition control module.
There is a chance that the Pole piece inside the distributor can cause a no fire condition. Last resort it could be that.
If you need more assistance, please feel free to follow up, I'll help as much as I can.
Hope this helps.
JUST advice from experience.
Good Luck
Paul