Hello Everyone!

I have a 1990 Si with the D16a6 that was manual swapped by the previous owner. It runs ok with the automatic PM6 ECU but threw a CEL for the lockup solenoid and had some idling issues so I figured I should try using a manual PM6 to see if that resolved anything. After installing the new ECU I don't hear the fuel pump priming and the car won't start. When I swap back to the old auto PM6 the pump primes and the car starts up right away. I should mention that the old PM6's red light will flash when I turn the key to accessory, but the new one flashes once then goes off. Supposedly the new ECU worked before it was pulled but I haven't been in touch with the seller yet about my issues.

Do you think this is simply a bad ECU? The inside looks clean and all the solders look ok but I am far from an expert in that regard. Is there something else I have to do when swapping a manual ECU into an auto swapped car.

Thank you in advance

 

Single blink on the ECU at key on is normal. If it kept blinking that would be a malfunction code.

Automatics have an Interlock Control module, I don't know for sure how its wired and its role in the fuel pump circuit, but it might be worth researching.

You can also try jumping the fuel pump relay to get running manually and see if it starts.

 

Ok, thanks for giving me some stuff to try!

I'll look into the wiring of the fuel pump and module, I'm also going to try the new ECU in another ef this weekend which will give hopefully me some more clues.
in the meantime I'll jump the relay and see where that gets me