5EK Cat 3406 No Start

Hello, I'm new to this it's my first post hope it's in the right section. I've read over all the open posts on any Cat 3406 but none seem to help me resolve my current problem.

So I have a 94 Kenworth with a Cat 3406 5ek. It cranks and start only with starting fluid and runs fine. It's not loosing prime. There's no smoke while it's cranking. And the fuel pressure is good. What I've tried:
-replaced cam sensor
- ohmed harness from sensor to ecm
-ran new wires from ecm to sensor
- used a working test ecm
- removed from cover and checked gear teeth all are good

I've read through the diagram for vehicle and engine side and tested everything without finding anything. Iam not really familiar with these engines and I know this forum is full of people that are full of knowledge so any help would be greatly appreciated thanks to all.

 

Compression is good in all cylinders and when it's running it's got power and runs well. Something is just inhibiting starting electrically it seems.