97 Stalls/No Spark

Have a 97 Riviera non-supercharged with 47,000 miles. After driving for about 20-30 mins, it will stall. It can be restarted a few times and driven for a couple more miles before it will not restart again. If I let the car set for at least an hour, it will then start and develop the problem again. It has done this 6-7 times the past 4 days. When the car won't start, I can hear the fuel pump energize when you turn the key on and there is pressureized fuel at the schrader valve on the fuel rail. When I remove a spark plug to check for spark, there is none. Any ideas what the problem may be? Could it be the crank position sensor? Any tests for this or something else? Also, the check engine light does not come on when this problem develops, so no codes to guide me in my troubleshooting.

Have a 97 Riviera non-supercharged with 47,000 miles. After driving for about 20-30 mins, it will stall. It can be restarted a few times and driven for a couple more miles before it will not restart again. If I let the car set for at least an hour, it will then start and develop the problem again. It has done this 6-7 times the past 4 days. When the car won't start, I can hear the fuel pump energize when you turn the key on and there is pressureized fuel at the schrader valve on the fuel rail. When I remove a spark plug to check for spark, there is none. Any ideas what the problem may be? Could it be the crank position sensor? Any tests for this or something else? Also, the check engine light does not come on when this problem develops, so no codes to guide me in my troubleshooting.

sounds like the ignition control module is getting hot and quitting:banghead:
ran into this problembefore on a gm
it is located under the coil packs

This does sound like the crank position sensor (CPS), however it could also be the ignition control module (ICM)! If it were my car, I would start with the cheaper of the two, and replace the CPS first.

This does sound like the crank position sensor (CPS), however it could also be the ignition control module (ICM)! If it were my car, I would start with the cheaper of the two, and replace the CPS first.

never seen a cranksensor that starts working after it quits although there is a first time for everything

never seen a cranksensor that starts working after it quits although there is a first time for everything:screwy:
Not sure what kind of cars you own or work on, however, on GM vehicles with a failing CPS, this is quite common!

If the crank sensor is failing due to heat soak, you will not have a CPS 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 CPS signal.

You can test the crank sensor resistance while it is cool and it will probably be within the range of the spec. The spec on the crank sensor should read between 700 and 900 ohms. The problem most people run into when testing the sensor is, they usually test it at ambient temperature, not when it is hot.

When you have an intermittent CPS problem, the best solution is to remove the crank sensor, place it in a pan of hot water and hook up your DVOM to watch the sensor's resistance as it warms up. (Check it all the way up to a boil). If it is a bad sensor, resistance will increase, until it suddenly goes open. (That is the point where your car will either, refuse to start, or simply shut down)! Now, pour out the hot water and add cool water and conduct the test again. You can watch the resistance fall back into the normal operating range. This would explain the no start problem when the engine/sensor is hot.

Now, another test you can try that can tell you about same thing without removing the crank sensor. Keep 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 what we suspect here is true, when the sensor cools down, the car will start and run normally, until the next time it overheats!:frown:

Hi, Thanks for all your replies, they helped me isolate the problem. Turns out that the base of the ECM has a crack on the front corner. How did this crack you ask? Well my wife rearended a pickup awhile back and this must be when it happened. I did the suggested water cool down on the CPS and this did not make the car start. So, I then focused my attention on the ECM and found the crack. Now my only problem is trying to locate a new ECM today so I can get the car running correctly. Thank you all for your help!!

COS, she cracked the ECM that is the passenger footwell? How hard did she hit the poor guy? Or was it the ICM with the coil packs?:confused:

It was the ignition control module "ICM" with the coil packs that sticks out beyond the side of the engine toward the front of the car a bit. It was tough to see until I looked at it real close in the sunlight. A small crack on the right side just behind the corner of the module. Sorry for the wrong abbreviation.