Hey

I have a 1991 EA falcon and the centerpoint injection kicked the bucket a month or so ago. The 4 speed auto was feeling super tired and had issues as well, so I decided to do a manual conversion and a MPFI conversion at at the same time because I found some cheap parts off of a 3.9 MPFI EB1 manual donor car.

The MPFI conversion tutuorial suggested to modify the existing CFI loom, but since the donor car was a pre-smartlock EB with MPFI, I thought it would be easier to swap over the ECU and the corresponding engine loom without issues, and this would make the manual conversion easier also.

Everything plugged in nicely apart from the plug between the ECU and the dash loom, behind the dash. I wired the corresponding colours up but there were still a few wires left over that didn't match. I have tried looking at wiring diagrams online but they only show one wire and what it does. Perhaps the online wiring diagrams are missing a few other pages. I have purchased a workshop manual but it will take a week or so to get here.

I tried starting the car with that wired up that way and the fuel pump didn't want to prime. I tested it with a battery and the fuel pump does work.

Just for testing purposes I wired in the fuel pump off another battery and tried starting the car. Nothing still.

I also did a small test for spark on #1 but it didn't look like it had spark. That's all I had time to do though today.

It almost feels like the ECU doesn't think the key is 'on' so doesn't bother with spark or injectors. The car does turn over with the key though which has got me confused.

So a couple of questions, was I ambitious to plug the other loom in and expect it to work? Even though they are both pre-smartlock and everything plugged in apart from that one plug?
Does anyone know what that white plug closest to the ECU plug is for/what the wires in it are for? I have seen a couple of suggestions towards instrument cluster things but nothing 100% yet and that wouldn't explain the issues.

Any advice would be appreciated. Would prefer to get it running with this loom but if push comes to shove, I might have to swap the Centerpoint loom in again and modify it to work.

Thanks

My CFI conversion did that too.... But I was using an auto trans - it turned out to be the TPS wiring (green, orange, black wires) - the CFI has two sets, the MPFI had one. I matched up the colours, but turns out that just because the colours are the same, doesn't mean they go to the same places...

I unplugged the TPS wiring and the pump primed perfectly

I will try that. Fingers crossed. Don't think that would be stopping the spark and fuel too though. But each step is a step in the right direction haha.
Thanks

It certainly stopped the fuel in mine. I don't know about the spark, as I was too busy ripping my hair out trying to find out why there was no fuel

Turns out that there was a massive muddle up with the looms and they were quite different. I managed to trace the wires that were different and hooked them up correctly and now it runs perfectly and primes and everything.

Thanks for your advice man. Much appreciated