I did a large port 4ag swap into an sr5 and when I turn the engine over it runs for about 2 seconds then dies.
I unplugged the cold start injector and the engine wont start at all.
I checked voltage to the injector plugs and both pins have 12V going to them.
when cranking the injectors don't pulsate so im guessing the ecu isnt sending a signal

Not sure where to go from here

First time doing this swap so any help would be appreciated.

Ill also add that i am running an external fuel pump mounted below my fuel cell and
using the stock sr5 feed and vent lines to deliver the fuel.

Ground wire/s connection under the intake man. have been mentioned 'bout 50 times in the past for this situation.

Thats what I came up with when I searched the forums along with needing a resistor for the low ohm injectors witch I have. "checked voltage in and out everything is 12v"
any thing else that would cause the ecu not to ground the injectors?

Sounds like an AFM/COR problem to me. Is the AFM hooked up properly? Could there be any big vacuum leaks?
If you have your diagnostic box you can jump the fuel pump in there bypassing the AFM interlock. If this allows the motor to run then your problem is in that circuit or the AFM.

Tried jumping the FP in the diagnostic box with no luck.
checked all vacuum hoses and there dosen't appear to be anything missing.

Does the fuel pump run when you jump it?

I have an external pump that is not run to the factory relay.

can somebody explain to me how the distributor and coil/igniter work to send a signal to the ecu to ground injectors?

The pickups inside the base of the distributor send signals to the
ECU to tell it the engine is running and the injectors need to be fired.
If you have a broken/shorted wire/plug not pushed home/bent pins
around the distributor, that can stop the injectors from firing.

The igniter generates an IGf signal to the ECU to tell it that an
ignition event has taken place. If the IGf signal does not reach the
ECU the engine will shut down. The ECU fires the injectors by pulling
the injectors to ground internally. That is why you have to make sure
that the three brown wires on the single brass ring connector are
bolted down. They are under the injector wiring plastic cover at
the rear of the engine on the intake side... kind of hard to see.
If thet ring connector is not bolted down the injectors don't fire.

Cheers... jondee86

i had this same exact problem. engine codes were pulled and the ecu wasn't getting a signal saying the engine had fired. i swapped the ignitor and everything was fine. then i swapped back the old ignitor and it worked perfectly fine. you might want to just try unhooking your battery for a couple of minutes and letting it reset, or swapping an ignitor. i have a 4age 20v blacktop

my igniter went bad the other day for some reason. no Idea what happened but now I don't have voltage when I check the positive of the coil to the case of igniter. Ill keep you posted once I get the new one in. Im thinking I have a short to ground somewhere so ill be triple checking my wiring in the meantime.
Thanks for the help guys