Hello all,

I have 1988 Chevy Suburban 5.7L, TBI, that have been fixing up. When cranking I have no injector pulse but can spray starting fluid and starts and idles fine. The truck wiring harness, distributor, oil pressure switch, fuel pump and ignition switch are all new. When I turn the key on, I can hear the fuel pump turn on for about 20s and then turns off. Won't start with TPS unplugged. I used the attached ECM connector identification to check voltages in/out of ECM. Pin D14 and D16 for injectors do have 12v with ignition on but when engine is cranking they drop to 0 volts. Is that correct? Also, pin C2 only has 0.6V not 12v like diagram indicates not sure if that would make the injectors not pulse but everything else checked out fine. I did buy a remanufactured ECM but still have the same issue. Not sure what else to check but any help would be greatly appreciated. Thanks,

 

The injectors should have power during cranking. The ECM controls the ground in order to fire the injectors. If the power to the injectors is cut-off, it won't matter if the ECM is properly grounding them--there's no current flow, therefore no fuel spray.

Find out why the power to the injectors is interrupted during cranking.

 

Thanks Schurkey. So when ignition is on I have 12v to pin A6 but when cranking it goes to 0v. When cranking should pink ignition wires have 12v?

 

A6 = Ign / ECM fuse

Yes, I'd expect that to be powered during cranking. Failed ignition switch???