is your battery in good condition and fully charged? is your starter good?
A bad starter can cause a Mercury Grand Marquis to not start. A bad alternator or a problem with the security system can be the cause for the car not starting.
try replacing the alternator
did you unhook the battery before replacing the alternator
a timing chain has broken
alternator
Start replacing the 2000 s10 alternator by disconnecting the battery. Remove the air inlet hose, and the serpentine belt. Take off the bracket over the alternator if it has one. Unbolt the alternator and disconnect the wires. Reverse the procedure to install the new alternator.
You need to replaced the starter or the alternator.
It could be the alternator or an electrical issue
A faulty alternator will cause those symptoms. You might want to get t checked out.
Alternator fails to supply power.
Dead battery, car will not start
on the 4.0 jeep, if it cranks, but wont start, try replacing the crank sensor, located at the top rear of the engine, at the transmission