fuel injectors not firing

I have an 89 gmc 1500. The fuel injectors will not fire. I have power going to the injectors. They will fire when I ground them. I have replaced the ecm, and checked the wires going from the ecm to the injectors and they are good. Is there a fuel injector relay, crank sensor? Does this truck have a keypass system? The injectors do fire once every now and then when you try to start the engine. No codes when hooked to a computer. Thanks for any help.

Replace the ign module in the dist and check the wiring, look closely at the pick up also..