My injectors have no power going to them. i just replaced fuel pump and relay. i have fuel going to my 350 tbi but nothing coming out the injectors.it wont start and i have no power at the injector so i dont know if its the ecm or what

Need vehicle information to look at diagrams for your system .

First, make absolutely sure the fuel pump is running when the key is on and is pushing fuel to the TBI. Take the feed line off the TBI if you have to. Watch it, fuel will spray everywhere if you aren't careful. Most fuel pump "no run" problems are caused by a bad ground. Use a VOM to check for power and ground.

Make sure the injectors receive power when the engine is cranking to start. Might be something as simple as a blown fuse. Can check with a noid light or 12v test light. Remote possibility of the injectors losing power when via the ignition switch and/or wiring when you crank the engine.

Fuel pressure regulator may be defective. TBI must be disassembled to replace it. There is a nice aftermarket adjustable regulator available.

Internal to the TBI itself (SOME, BUT NOT ALL HAD THIS) is a small neoprene pressure bleed. It has a VERY small hole in it, used to slowly bleed off the fuel pump pressure when the engine is shut down. If the diaphragm ruptured the fuel will return to the tank, never building enough pressure to spray out the injectors.

These units are relatively easy to rebuild. Youtube has several good vids walking you thru the process if you have any doubts.

Replace the pickup coil in the distributor this is where you get your pulse for the injectors.

The fuel pump circuit and injector circuits are fed by two different fuses.
The fuel pump relay and injectors are controlled by the computer. Have you checked both ECM fuses for power ?

When you say the fuel pump relay is good did you test for power to the relay circuit ?

you may wanna replace your injectors them self

check your fuel regulator

Make sure you are getting power to the injectors. I have the same,350 tbi. Check the fuses and relays and check the wires at the tbi to make sure one of them is not rubbed through. The injectors have to be getting intermitent power .

Fuel pressure is a little low, check the pressure regulator, and the fuel filter

I have a 90 chevy k1500 350 tbi with same problem! I have traced problem to... after turning on key fuel pump kicks on when u crank it over injectors shoot gas and truck starts! After few seconds injectors stop spraying and truck dies! This can happen many times over and over! Eventually sometimes truck stays running and all is great! I changed ignition module, oil pressure sending unit (which i was told controls gas after vehicle is running) fuel filter, computer, fuel pump relay, I am at a loss now! Hope this helps and hope someone can help me!