i am finishing my 89 iroc tpi to carb conversion, edelbrock performer manifold and carb and i'm going to keep the ecm installed so my vats security system and the auto trans converter lock up will work. i also want to use the fuel pump relay with my new outside the tank electric pump with fuel pressure regulator. my question is, will all this work correctly if the wiring is kept correct and not disturbed. the engine starter cranks. i will know if the fuel pump works once i am through with that installation.

 

The ECM has nothing to do with the VATS - so no need there.

I'm not sure how exactly, but the TC lockup is controlled by the computer - but it's electronic, and since the ECM won't be getting the correct inputs from the engine anymore, I don't think it will properly lock the TC - someone with more experience chime in here.

You can use the relay all you want - but the powert hat the fuel pump gets from the relay is only for a short (2-3 seconds) time - just enough to 'prime' the pump for the fuel injectors (ie it pumps fuel up to the injectors that don't hold fuel - whereas a carb holds fuel in the bowls to start the car until the pump gets more fuel to it). The in-tank pump is actually run (after the car is started) by a 12v+ wire that runs directly from the battery through the Oil Pressure Sending Unit (OPSU) to the pump. Thus the pump gets power from two independant sources - 1) from the relay which is powered by the ECM for only a few seconds to 'prime', and 2) directly from the battery through the OPSU - this is where the constant power comes from.

So - in the end there may be no need to keep the ECM installed - unless there's a way to rig the TC lockup to work through the ECM.