1999 Grand Marquis turns over but won't start

It could be a number of things but it seems more heat related. Cheeck the fuel pressure when the car is cold and then hot and see what your reading are. It could also be your coul packs and or wires Camshaft sensor could be bad or starter or stater relay...

Is the check engine light on?

No check engine light.... And when it's running it runs like a champ. You barely even hear it...smooth. I thought it was heat related but it's been a couple days now and it won't start at all.

I wonder if it is related to the fuel pump, or fuel pump relay? Checking for proper fuel pressure would be helpful. Usually a crank or cam sensor will set a code and light the check engine light.

Gonna try a couple things tomorrow...I'll update after

Uhh, it's been a year.......

Having the same problem with my 99 marquis last few months,, so far Im thinking the electronic control module, had a ford a few years back did the same thing and it turned out to be the ecm

curious if you turn the steering wheel as you are cranking the engine will the vehicle start then die``

Did anybody ever fix this issues 04 grand marquis

I have been working on my mother in laws 2000 Mercury Grand Marquis with the same problem. Her son thought it was a cam sensor and replaced it. No good still. He then replaced the fuel pump relay. No good still. They could hit it starting ether and it will start, so they thought it was bad gas and added fuel stabilizer. The same day I came over after the fuel stabilizer was added and the car wouldn't start again. It eventually started. Runs beautiful. I took it home and replaced the IAC valve and scrubbed the throttle body with choke cleaner. It was really carboned up. I have been driving the car for the past two days on the same tank of gas and it has been starting every time hot and cold. We were out at a store for about a half hour in 50 degree weather and the car would crank quickly but wouldn't turn over. Pushed the gas pedal all the way down and removed my foot quickly allowing the gas pedal to snap back up and the car started up again instantly. Now I am thinking maybe its the butterfly valve and whatever that other little electrical device is on the end of the butterfly valve on the outside of the throttle body next to the IAC valve. Any thoughts?? What am I missing?

I unhooked battery, both cables, restarted right up ran several days just fine. Than happens again. Treated it like a computer and rebooted it. Got rid of it. Think is was ecm...