91 LaSabre wont crank when hot

i have a 91 LaSabre that once it gets hot wont crank, have replaced the fuel pump, mass air volume control, and coil pack,....any more suggestions?

If the crank sensor is failing due to heat, you will not have a CKPS signal, or spark to the plugs until the sensor cools down! If you have a tachometer or scanner, check for engine rpm while trying to start. No rpm would indicate, no CKPS signal.

Put a gallon of water in your car for the next time it stalls. (If you have a pump garden sprayer, that would work better)! When the car stalls and will not start, open the hood and pour, or spray water on the crank sensor to cool it down. If heat soak is the problem, when the sensor cools down the engine will start and run normally, until the next time it overheats! If cooling the sensor down works, replace the sensor.

There is a coil pack drive board that sits underneath the coil pack. They do have a tendency to do many silly things. One is to stop working when they get hot. You said that it would not crank when hot. I don’t know what you mean by that. If it runs fine until you shut it down and buy a soda at a stop and rob. Then try to fire the engine and it does not. I would pull a couple of wires off the coil pack and see if you have a Frankenstein light show when you try to start the car. If you do that is not the problem. If you don’t have a spark show, I would bet that it is the board. This is why. That board fires the coils below 500 RPM. At 500RPM it hands off the task to the ECM. To start sparking that board requires one pulls from the crank and one pulls from the cam sensors. If it was running fine when hot, and not tossing a code, but won’t re-start, it is the board. Now that Old girl is a 3800 type I with OBD I compliant ALDL connector so I am not sure if you can monitor and graph the sensors with a good scan tool. But you can always back probe the connector and look for the signals to and from the ECM, and from the sensors. ( I did that for years) There is a handshake going on. (A, I have it or you have it type of thing.) That needs to be checked before you toss out the cash for that board. And by the way, you can swap out the brick type and the individual coil type at will. They do the exact same job, have the same mounting system and the same wiring harness. If you have a brick type they are notoriously bad.
At this point the easy way to test it would be to beg barrow or steel one from another 3800

by getting hot i mean if i drive less than 4 miles to the store and come out it wont crank ...maybe an hour or so to cool down, when the coil pack was replaced on friday it had this yucky sticky stuff oozing out of it, could that have damaged the board you are talking about??? thanks for the reply, its breaking me have spent 550 dollars already and still same problem....

im on jury duty, will carry the water with me..thanks for the help...willing to try anything at this point have spent 550 dollars

by getting hot i mean if i drive less than 4 miles to the store and come out it wont crank ...maybe an hour or so to cool down, when the coil pack was replaced on friday it had this yucky sticky stuff oozing out of it, could that have damaged the board you are talking about??? thanks for the reply, its breaking me have spent 550 dollars already and still same problem....

Yes; that is the type of failure I was trying to describe. It is also the reason why I sugested that you beg barrow or steal another IM from a friend or unsuspecting neighbor. It either is not getting Juice on the pink/black wire from the ignition, or there is a usually a problem with the Electronic ignition module start mode. There is also a tan and a blck wire that may be staying high. You see if that car will run all day long without missing a beat, but not start after a 240 seconds of running, that points to an iffey AIC, or that Ign module. It has two parts. One that starts the car (the part I think is bad). And the part that is a solid state relay so that the ECM, the coils, and all the sensor data can get passed to where it needs to go. And just so that you know, the white wire that comes out of that is the wire that goes to the instrument panel for the tach.
Before I would go dumping water all over the place…….. You can buy what is called component cooler at radio shack. It also goes by the name Freeze It. If the zit face kid working there has no clue, just ask the Manager or look around the soldering irons, etc. The can is about 8$ and just a tinny little shot will cool anything down. I don’t think that it would work on the ignition module because all the important parts are hidden inside a box filled with that silicon snot stuff. In any event if you look behind the plastic cover on the passenger side, you can give a 3-5 second burst of that cool it to just the cam or the crank sensor to make sure that is or is not the problem. Without having water go all aver the place. It is hard to trouble shoot your car 1000 miles away banging on these greasy keys, But I think that we can muddle our way through this.

later

Before the day that I purchased a good scan tool, you would not believe how many hrs I spent with my O scope finding the problems

If I read your first post correctly, you have already replaced the "coil pack" and if so, which one does your car have, the Type I Magnavox or the Type II Delco? Type II has three coils mounted on top of the ICM as shown in the pics below, and the Type I Magnavox has the coils mounted internally. BTW, I included a schematic of the related wiring for you.
ACDelco

http://img454.imageshack.us/img454/3722/msdcoilsmg4.jpghttp://img74.imageshack.us/img74/7241/discoilpacksxb5.jpg

http://img254.imageshack.us/img254/6357/431az9.gif
(http://img254.imageshack.us/img254/6357/431az9.gif)

yes you read correctly, we replaced the coil pack, code said #1 was dead but it was all one unit, so to answer your question it was Type I...thank you for your information about the wiring..

Hot Z

That was absolutely great of you to post that schematic. I just wish that it had the relays inside the board that I was talking about. In any event it looks like my memory was a little off. I though that the ignition power was pink with a black stripe, whoops! If working without a scan tool, that comes in handy because you don’t have to start crawling under the car to find the signals that you need to “see”, they are all right there. (That is unless you find a cruded up plug or a bad wire). By the way it does not matter mutch on the type 1 or 2. If you change the board and the coils they are interchangeable. My father has an old zenith type 1 that failed all the time on his olds pre type 1 engine. I swapped the type 2 from a Buick medallion engine and it works great. (The medallion engine was also a pre type 1 engine with a different intake manifold and crank sensor.
Push come to shove I know that the spades fit and you can swap the individual coils in to the brick type and duct tape them down in a pinch. That is as long as it is not raining!

Three things hillbillies wont say
1.) Obscure Shakespearian plays for 2000 Alex
2.) Lets go to the Opera!
3.) Duct tape wont fix that


PS suprised that it is a type 1, GM learned to stay away from the zenith coils early in the game around , but olds stayed with them later in the game. I guess they wanted to use up there old stock.

Yes; that is the type of failure I was trying to describe. It is also the reason why I sugested that you beg barrow or steal another IM from a friend or unsuspecting neighbor. It either is not getting Juice on the pink/black wire from the ignition, or there is a usually a problem with the Electronic ignition module start mode. There is also a tan and a blck wire that may be staying high. You see if that car will run all day long without missing a beat, but not start after a 240 seconds of running, that points to an iffey AIC, or that Ign module. It has two parts. One that starts the car (the part I think is bad). And the part that is a solid state relay so that the ECM, the coils, and all the sensor data can get passed to where it needs to go. And just so that you know, the white wire that comes out of that is the wire that goes to the instrument panel for the tach.
Before I would go dumping water all over the place…….. You can buy what is called component cooler at radio shack. It also goes by the name Freeze It. If the zit face kid working there has no clue, just ask the Manager or look around the soldering irons, etc. The can is about 8$ and just a tinny little shot will cool anything down. I don’t think that it would work on the ignition module because all the important parts are hidden inside a box filled with that silicon snot stuff. In any event if you look behind the plastic cover on the passenger side, you can give a 3-5 second burst of that cool it to just the cam or the crank sensor to make sure that is or is not the problem. Without having water go all aver the place. It is hard to trouble shoot your car 1000 miles away banging on these greasy keys, But I think that we can muddle our way through this.

later

Before the day that I purchased a good scan tool, you would not believe how many hrs I spent with my O scope finding the problems


I have finally got someone to put on another coil pack and board, in fact 2, and its still doing the same thing...wont crank once it gets hot and not it hot outside too takes 6 to 8 hrs sometimes to cool enough to crank, any other suggestions??? im going crazy here...

thank you

I have finally got someone to put on another coil pack and board, in fact 2, and its still doing the same thing...wont crank once it gets hot and not it hot outside too takes 6 to 8 hrs sometimes to cool enough to crank, any other suggestions??? im going crazy here...

thank youHave you changed the crank sensor? Do you have spark to the plugs when it stalls?

It is your crank position sensor. I am sure of it....

It is your crank position sensor. I am sure of it....I had the module under the coil packs go out on me once and two cylinders were completely dead, even with a cold engine. I had your same problem just recently, I change the CPS and all is well now....