So recently I purchased a 91 SI and it seems like there is a fuel delivery problem. I changed a few things:
New fuel pump (had to hardwire to a switch on the dash)
fuel filter
cleaned injectors
cleaned fuel rail
blew out fuel lines
cleaned tank
new fuel
I tried a different ecu out of a crx and a new main relay too.

It starts when ether or fuel is sprayed directly into intake, but dies soon after.
Any ideas????

 

A wild guess.. but what about the fuel regulator

 

Check that the injectors get power. There is an injector resistor pack under the hood that is in series with the hot side of the injectors (the ECU then drives the other side to ground). Get rid of the jury-rigged switch. Having to do that probably means that there is no power to the main relay from the fuse box, either a blown fuse or bad fuse box or harness. Even a new main relay should be taken apart and resoldered.

Disconnect the fuel return hose from the regulator at the firewall and confirm that fuel comes out when the pump is running. This is better than disconnecting at the filter because it proves the pump is making enough pressure to open the regulator (assuming the regulator is good).

Also check the timing and compression. If the gas in the tank is stale it will be very hard to start.