Donor Wire Harness Problem

[rrisdon]

I have asked in the past about fuel pump and fuel pump driver module problems that were the apparent culprits preventing my MK IV roadster build from starting. We have tested every power connection and all have power except for output from the ECM. There was an occasion where unplugging the ECM and reconnecting had power out and the car started and ran on three separate consecutive occasions. Then there was no output again from the ECM. I assumed there was an issue with the ECM and had it bench tested at BBA Reman. They said it tested perfectly with no issues found. Now I'm really stumped as to what to do next. I am using a 2001 Mustang Cobra donor engine, tranny, wire harness. Any suggestions would be greatly appreciated.

[AC Bill]

Do you have the ECM's ground wire connected? This wire is part of the donor harness, Usually it's right close to where the large connector plug is for the ECM.
I think, (although it's been awhile), it has a star type eye connector on a green wire least on the early 5.0 ECM's.

[Timb]

Are you using a piggyback chip in the ECM? Sometimes if they are installed without cleaning the contacts well or securing them against vibrating loose you can get some intermittent issues especially if it is being used to disable pats