My '92 sedan turns over and starts briefly but dies seconds later. This
started yesterday morning, few months ago I had the alternator replaced
and had no problems until now, any advice?

 

If the Check Engine Light (CEL) is ON, the code(s) that you can retrieve might be informative (see picture). Otherwise, you should start by determining whether spark is detected at each plug. If you have spark, then consider problems with fuel getting to the cylinders, such as a clogged fuel filter, faulty fuel pump, or bad main relay circuit.

[IMG]local://upfiles/25538/A0FC386331574B68A91102BC70382740.jpg[/IMG]

 

check the starter solenoid