I have a 1990 bronco II, 2.9
It’s got an issue where it will fire up but it won’t restart after it gets up to temp.
i just did a top end rebuild and put a new tank and fuel pump in to try to fix that but it didn’t work so I bought a new ECM.

With the old ECM in it, it fired up and ran fine/ everything worked as should. With the new ECM in the truck it will not send fuel, I’ve checked the relay and the connection on the pump and it’s fine. The new ECM will just not activate the pump.

side note; when I turn the key I can hear a faint clunk coming from the pump, when I put the old ECM back in the pump works fine.

 

What lead you to believe the ECM was the problem? Were there KOEO fault codes? Fuel pressure tested within specifications not hot and cold? Were you losing spark once the engine was hot?

It sounds like the reman computer is bad.