1991 firebird formula 5.0L, VIN F, multi port fuel injection, vehicle will not start since the injectors never receive a ground from the ECM. NO CODES! Replaced ECM, did not help. Checked continuity from 12volt supply through fuel injector wires to input connectors on ECM, everything OK. Original problem was, vehicle would start and run 20 minutes then shut off, no grd for injectors tto fire. Never had a code. Pulled TPS sensor connector got a code for it from the ECM. Can the MEM/CAL cause this problem? I had no Code 51

 

Are you sure it’s a ground issue not a icm problem?

 

The ecm provides the ground for the injectors, they have 12 volts applied to them all the time and the ecm determines which injector to ground based on what the distributor module tells it. To test, I applied a test light to the two leads of one of the injector connectors. When vehicle runs light is on, I checked this out when it was able to run for 20 min. at a time. When it stopped running (like it ran out of gas) I tried to start it and had no light at the injector connector ecm not supplying a ground for the injector

 

Have you used a noid light to check for injector pulse ?
Here is a pinout for your ecm grounds located behind your passengers cylinder head.
http://tpiparts.net/1227730_pinout_diagram
Even with a bad memcal in limp home mode you will have injector pulse.
This is a batch setup the ecm doesn’t fire one at a time.
A shorted injector will shut down the injector driver and kill all eight injectors.
Especially if these are the stock multec injectors.



https://www.southbayfuelinjectors.co...1985-1992.html

 

Would def ohm check the injs, esp if they are stock.

 

yeah I would check the ignition control module. I believe the ECM uses the signal from that to drive the injectors.

injectors use a switched ground from the ECM with a constant 12V supply. Thus ohming out the ground side of the injector harness with the engine off won't be useful.

 

Did you resolve this issue ?