Hi Thirdgen community,
So I have had the same problem for 10 plus years now I have an 86 camaro z28 iroc and I swapped the 305 block with a 350 instead! While it's a beefed up motor and new I haven't been able to get it running so I'll break this up into 3 parts so everyone can get the gist.

After installation of the 350, instead of buying a ECM from GM we took one out from my 86 corvette figured that would work, and it did! Only problem was as far as we could guess the VATS kicked in from the corvette ECM so after running for 30 seconds or so it stopped and we couldn't get it to run ever since.

We pulled the 86 corvette ECM out and put the old one in and everything worked, it would turn over we had everything except for injector pulse, nothing we would do would get those suckers to fire unless we shorted them and we did to all 8 to check so they work but not from the computer! We called the wiring he found out that our ground wasn't perfect so one problem solved but still nothing!

So after that we took the 86 camaro to somebody who had us buy a new ECM before he would start working on it, he determined that there is a wire somewhere that is probably fried and that's what stopping the injectors from pulsing but after going through and checking the injector wires as well the one that runs to the ignition and ECM they are fine

So my question to you guys is where do I go from I bought a new painless system but it seems some connectors are in the wrong place,

Also besides that point maybe someone can point me in the direction of the wires I should be testing or which ones might be bad that I should check any help would be appreciated me and my dad put it together when I was 20 i am 30 now and only want my 86 back up and running!