Ok, I have a 91 Z28 305 TPI motor, it ran after I bought it, but shortly after I found out the bearings were bad, so I pulled the motor, flipped it over, replaced the bearings and timing chain (motor never smoked so I didn't mess with the heads or pistons) Put it all back together, threw it in, but now I can't get it running. I just replaced the fuel pump and it works fine I hear it and everything, I also know the motor is good cuz I've started it by spraying gas into the air intake and it fires up great, but some of the wiring is a little fugly and I have the pump working and I know there's fuel in the fuel rail cuz I checked the line valve and also a week ago an injector was spraying gas onto the intake cuz I needed an O-ring, I put it on, doesn't leak, I have pressure in the rail. I also checked the injectors to see if they had juice and the test light lights up when I touch it with either of the 2 wires for the injectors, but the problem I'm having is that the injectors won't fire and I know they can't all be gummed up because they worked before, at least one should fire, so I think its a ECM or wiring problem. Do the injectors need any kind of ground? or is there a ground for the ECM on the engine? I was going to do an ALDL test, but my check engine light doesn't come on and I checked the bulbs for the instrument panel and they're good, so I'm wondering if its the ECM. Another thing I did was disconnect the TPS sensor and re-connect it, but it hasn't been adjusted. My plugs and plug wires and distrubutor work fine because i've fired up the engine using gas into the air intake, But I'm wondering why the injectors won't fire and keep the car running. And advice? Info? I need to know what needs to be working to make the injectors fire. Any help would be greatly appreciated

Couple of things could be giving you problems here.
The ECM provides the ground path for the injectors. Confirm all grounds are connected good at the back of the heads etc.
You have the ppower at the injector wires so that end is good.

VATS would be enabled in the 91' so you would need that to be functioning to get the injectors to fire.

The TPS will give no fuel if it reads over 80% signal.
Connect it and confirm your starting position is 0.4-0.6 volts and it goes up to oner 4.5 volts when held wide open.

Distributor pulses would be needed to indicate the motor is turning. If the fuel pump starts and runs when cranking that "should" indicate the distributor is working. Also if it runs with gas sprayed in then the dizzy should be fine.

Yup thats what I would say too...check all grounds...the test light shouldn't light up on both prongs of the injector plug...you should have 12v at one side of the injector plug with the key on...and the ECM controls the ground with a transistor (high speed switch)....you definitely have spark if it runs on gas sprayed in the intake....if you have the same key and haven't touched any of the wiring on the VATS module then it should be fine...but always a possibilty so check it out...but more than likely its a botched or corroded ground causing your problem...