Sorry to bring up an old post, but I've been having the exact same problem as mentioned above. First off, the fuel pump was bad and I had to change it, now I'm getting good fuel pressure at the TBI unit. (350 tbi 88 1500)
Swapped in a jy distributor w/ ignition module and pickup coil untouched, and still fuel injector problem.

The fuel injectors will not spray, but the motor cranks over with starter fluid/ether. I swapped the connectors on the fuel injectors to use the secondary injector (inj #2) as the primary (secondary is used at higher rpm or WOT) and still no spray, so I know the injectors are good. I tested voltage and I'm getting voltage on A6 out of the ECM, 11.98v, and voltage at the fuel injector pigtails 11.8ishv, and voltage at the pinouts on the ECM... D14 and D16. after these pinouts, the ecu grounds them and the circuit is closed and you get spray.

I checked the ignition module and it's getting power in on the two-wire connector coming off the ignition coil.. and the four-wire connector I'm hardly getting power when the ignition is in the ON position. I checked the pinouts on the ECM B3, B5, D5, and D4 with the same results. Do you think I just have another bad igni module?

What other sensor,etc keeps the ECM from grounding the fuel injector's circuits?

Thanks for any help.. here's the wiring diagram schematic



btw all fuses are fine, etc