well i replaced the therostat yesturday and i connected everything back and tryed turning on the car fuel pump is not priming nor the ecu turns on when i turn the key. its a 90 civic with an ls swap it was running fine before i replaced the thermostat. i have checked main relay and all the fuses . im stumped not . any help would be great thanks

 

There is a ground that connects to your thermostat housing. Look around there and see if you can locate it.

 

yea i connected it back where it was at . on the housing could it myabe have a a bad connection?

 

Well its possible. Just make sure its tights on the housing.

Check the ECU fuse in your fuse box in the engine bay. I think its #10. But dont hold me to that. Just look on the fuse box cover and see where it is. It sounds like that fuse blew.