93 eldorado starts and imediately stalls

[fmczz72]

My brother has a 93 eldorado that starts and then imediately stalls. only runs a few seconds. This started right after he changed his thermostat. Not sure if they are related.
I've worked on many cars but I don't know much about Cadillacs.

Any ideas????

[maxwedge]

Welcome to AF, does it restart? If not do you have fuel pressure at the rail and spark, basic diagnostics.

[fmczz72]

Yes, it will keep starting and imediately shut off, over and over. I have not checked fuel pressure yet. I assumed it has spark since it continues to restart.
Someone suggested the security system.
It just seams odd to me that this started right after he changed the thermostat. It stayed running right before that.

Thanks

[maxwedge]

Take a look around the t'stat housing for any disconnected or loose sensors, there is no quick answer here from our desks, these diagnostic/checks must be done from under the hood, naturally.