Seemingly Random No Start- 01 Grand Marquis

[NYEngineer]

Maybe you guys remember me asking a while back about purchasing an 01 Grand Marquis with 24,000 miles? Well, we picked it up and it's super clean and for the most part, we couldn't ask for a better used car. The ONLY thing it does from time to time is this... My stepson will drive it somewhere, shut it off, go to get back in and it refuses to start for 30 minutes. Twice, by the time I got there, it started, so I had nothing to go on.
I removed the engine cover and checked the fuel pressure and it was about 34 PSI and rock steady. We took it for a couple of rides, shut it off and it restarted every time.
I know this is reaching, but I figured maybe the engine cover was trapping heat causing the fuel in the lines to boil and vapor locking it until it cooled. With the cover off, it was fine for a couple of weeks until today. It did it again. I was at work, so over the phone, I instructed him to check the valve on the fuel rail and he said he got solid fuel but the car still only cranked and did not start.
Maybe a crank position sensor going bad or something? I'm not getting any CEL. Anyone have any ideas? Thanks in advance.

 

[SuperEd73]

I'm thinking it may be something totally different. Does this vehicle have any sort of alarm system or security system involving a chip in the ignition key or anything like that? I've heard of security systems shutting down the fuel and/or ignition system to prevent startup.

 

[NYEngineer]

It DOES have a big key with some sort of transponder on it. Interesting.

 

[01rangerxl]

It could be the PATS (passive anti-theft system) acting up. Does your stepson use a different key or anything? How does he unlock the car (key, remote, key pad on the door)? I'm not sure what it could be, but if you can figure out if he is doing something differently than you, it could point you in the right direction.

PATS will allow the car to crank, and sometimes fire for a second, but it won't run.

 

[moribundman]

Does that engine's ECU require accurate coolant temperature info? If so, the coolant temperature sensor may be wonky.

 

[Colt45ws]

If the check engine light shuts off while cranking(provided it is normally off when the car is running and no codes set), the ECU is receiving a Crankshaft signal. If it does not, the sensor is suspect.

 

[AcuraTech]

I would lean towards an engine sensor of some sort, intermittently putting out a bad signal which is cutting spark or injectors.

Without a CEL, you just have to keep narrowing things down. Intermittent no start problems are a PITA! See if you can find a forum board of people with similar cars to see if it's a common problem. 9 out of 10 times when things on a car go bad, it's a common recurring issue with that particular make.

Good luck!

 

[NYEngineer]

Originally Posted By: 01rangerxl
It could be the PATS (passive anti-theft system) acting up. Does your stepson use a different key or anything? How does he unlock the car (key, remote, key pad on the door)? I'm not sure what it could be, but if you can figure out if he is doing something differently than you, it could point you in the right direction.

PATS will allow the car to crank, and sometimes fire for a second, but it won't run.


The car only has one key. It has a transponder or something on it. There is also an aftermarket alarm with remote locking and unlocking of the doors. As far as I know, he only locks and unlocks the doors with the remote, gets in, and starts the car with the key. We don't know the keypad code on the door.
It does exactly what you're saying. It cranks and fires for a second. If you wait thirty minutes, it's fine.
I'm thinking this is the lead I need. Thanks, everyone.

 

[eljefino]

If the car has a security key there will be a security light on the dashboard that'll be going nuts if it's malfunctioning/wrong.

I'm betting on a bad crank sensor, they're usually hall effect coils and kinda touchy and can do this on again, off again failure mode.

 

[mechtech2]

Heat failure is usually electrical components.
I despise alarm systems, as they can be impossible to diagnose or repair. but this may be your source of grief.

Maybe an ignition component - coil or module.