im not too sure what you mean about Hall effect output,
if i get you though , you are saying:
you have a Fuel injector that has an output of 12 v that goes to 0 on a trigger and has spark control
you have a Distributor(spark system) that fires on a negative trigger, that goes from 12v to 0 on the input
sounds to me that they are made for each other, maybe let them touch a bit!? , maybe wear insulated gloves
testing the spark system by using ammeter on trigger will show if there is high current on trigger(which could then be a problem)
but this is advice from someone with little experience in either field