usn_crx

Also, the swap wiring is not a concern, as I have been driving it for about 3 years now. It just quit on me as I rolled to a stop at a traffic light a few weeks ago.

83Stang5.0

You had said you checked the coil, so you really didn't? If you have no spark, check the coil. Easiest thing to die randomly to cause a complete no start situation.

usn_crx

I changed the coil, and there was no change in what it did.

usn_crx

I did just verify that I have spark at the plugs. The red LED on the ECU flashes when the key is turned on and off.

Fabrik8

You're saying that it can't be broken because it wasn't broken before, but something broke.

usn_crx

Fair enough, I'll be more specific...what I meant was that it is not a new swap, so how it's wired is not a concern. Yes, it is possible that a wire from the swap is broken.
Thanks again for your help.

T-Hybrid#2

Check # 14 fuse under dash.. If not there then go to fuses under hood(ecu, ect.). If the main relay goes bad it would still turn over just wont crank. The relay sends signals to ecu and fuel pump/injectors. Other then that look into the ignition switch, Or ground wire on thermostat housing. Hope this helps.. I just went through sort of same issue and ended up being the #14 fuse. Make sure you pull it out to check just dont look at from the side..(could be blown at bottom.)
There is a way to check your relay with a volt meter. I have diagrams around here some where to do so. Will look for it . Relay cost 51.99 at auto zone as I just checked last week. But I'd make sure before i threw a new one at it. Also you can fix old relays, they usually have cracked solder joints inside them if you open up and see any bad joints just re solder the bad joints. Heat causes them to get weak and break. common issue

83Stang5.0

He said the ECU light flashes, so he's keying to run successfully, also the ECU light wouldn't flash if the main thermostat ground wasn't hooked up.

T-Hybrid#2

I know that>> just giving him things to check.. Could be loose or dirty.. Just know thats the main ground for the above stated.. Thanks

usn_crx

No luck with fuse 14. It read out with a meter, and I swapped it with one like it. Still no start.