What can I check and how?

Its turning over I can see the alternator belt goin but it wont start.

Shut off as I was driving on the highway. All the lights etc still come on.

Would the ECU Fuse failing cause this? What else and how would I check it?

 

If the fuse blew yea, or Igniter or coil or both.


check for spark,

clean the ecu ground on the thermostat housing, hint clean it real good, when you think you have it sanded and clean do it again or move it to a the head.

If this happened while driving I'd say igniter or coil.

In that case buy a rebuild dizzy, about $170.00 and comes with all new parts. Trust me, been there done that, the cheap way then ended up buying a dizzy anyways.

 

I have a spare dizzy laying around from my old motor so thats good.

Would this throw a CEL?

 

Also check whether the timing belt snapped or slipped.

Have you checked for fuel?