I am in the process of repinning my '747 into a '730 and a few questions have come up. One is the injector wiring. With the 747 the injectors look to be grounded somewhere other than the ECM like on the 730. Do I need to go and cut the ground wires off and run them right to the ECM plug or will they be fine where they are? Also, there is a crank sensor wire in the 747 harness that doesn't seem to be shared by the 730. Anyone know what I should do with this? These are the only hangups I have as of now. Any help would be greatly appreciated! Please let me know if there is any more information needed for this question. I am really stuck!

 

Please? Someone throw me a bone here! I am sure this has been done before! I am sure it is similar to the '746 ECM....

 

I don't have the 747 wiring diagram, but it makes no sense that the injectors are grounded somewhere other than the ECM. You may be overlooking something. The injector ground wires are dark blue and dark green. They are very stiff wires on the TBI motors. I really think those wires are going to your 747 ECM. Regardless, you need to connect those wires to the 730 ECM. You can not have some other ground source. The ECM fires the injectors by grounding the circuit...nothing else is going to control this functionality.

Ignore the purple wire that goes to the 3 amp crank fuse. It is no longer needed with the 730 ECM.

 

Thank you very much! THat is what I thought it was going to be like. I used up all the pins coming out of the 747 ECM, so I am trying now to figure out where else the other two injector wires go. Again, thank you.

 

The 730 won't take the extra load of trying to fire the TBI injectors. It will work for a while, but after enough time at high engine loads, the injector drivers will fail..

If you want to run a TBI with an ecm like the 730, then you need to run a 749, and wire it up like in the sunbird applications.

All the GM EFI, have power on one side of the injector, and the ecm suppling the ground to fire them.

No the 730 doesn't need to see a *crank* signal.

 

Ah, I was assuming we're talking about a TBI to TPI conversion. I guess we're both in the dark about this. I made the assumption because this is posted in the TPI board rather than the ECM board.

 

Right. Sorry for the confusion, I should be more specific. I am converting from TBI to TPI. Damn, I was in such a hurry I forgot the vital info! S10Wildside, you were right about that. I Guess I may of assumed that being in the TPI forum that others would assume the same thing. We all know what happens when one assumes! Please forgive me, you are all great! I would be lost if it were not for all the info on here.