Ok so i will give you a little back ground..

Bought a 5.3L with computer and harness to swap into my 88 mazda rx7...Put in a Ls6 cam and springs,ARP Rod bolts and Head Studs,melling oil pump,Cobalt SS Map Sensor,Ls6 Intake manifold,60Lb injecotors,Ls9 headgaskets,and im doing a turbo setup..

Now the problem i am having..
If i turn the key onto ACC i have 11.5/12.0V to both wires..
Now if I check it while cranking i get 9.6V, no ground..Anyone have any ideas? i have an RPM signal, i have spark, and i know i have fuel pressure at the rail...Checked all Pcm grounds through the red and blue PCM Connectors and everything checked out ok..

Im starting to think its a timing issue??

 

i know you said youve checked your grounds at the pcm connectors..but are there any ground that go on the backside of the driver cylinder head that need to go on? i know ls1's have this and i had a similar issue when my engine wouldnt start for the first time and it was these grounds on the back of that driver side head.

 

the 1st time we cranked it over that was a problem but we got that fixed and now see this injector problem..

 

Ok checked timing and even went out of my way and made a WHOLE new harness on the car and still seem to have the same problem!!

 

1. 9.6 v when cranking is low....Sounds like time to do voltage drop testing on the system. How is the engine/chassis/batt ground system hooked up?
2. Noid the injs to be sure the pcm is triggering them.
3. If 2 is "yes", are the 60# injs used? If so, how long have they been sitting?

Timing issue? What does the program have in it? NE codes set? What does your scanner say while cranking?
Pcm been modified to remove VATS, etc????

 

Like Old Geezer mentioned, it sounds like you didn't disable VATS in the tune.