94 Bonneville stalling

3.8 SE - 153K miles. Occasionally after driving the car for about 20-30 minutes it will stall. If I wait 15 minutes it starts up and runs fine. Check engine light does not come on or are any codes set. It was tuned up about a yr ago and fuel filter changed.
Any ideas on what i can check, when it is stalled to help troublehoot. Thanks for any help

Crank sensor, ICM & fuel pump have all been known to do this.

Fuel pump is more likely to do this when fuel in the tank is getting low. Best way to test fuel pressure is with a gauge. They run about $40 which is less than getting towed. You'll want to put some rags around the Schrader valve to absorb leaking fuel when attaching the gauge.

I like to test for spark with a spare plug. Just pull one of the front plug wires & put it on the spare. Set the base of the plug on something metal & look for spark while someone tries starting the engine. I don't know how you can check for spark if you're alone.

Thanks for the reply.
What is an ICM? Ignition control module?
How hard is it to replace the CPS? Do I need a puller?

Thanks for the reply.
What is an ICM? Ignition control module?
How hard is it to replace the CPS? Do I need a puller?
Go to autozone.com/repairinfo for the procedure on both these items.

Yeah, ICM = Ignition Control Module. Coils are mounted on top of it. I've never replaced a crank sensor but it sounds like the hardest part is getting the nut off the harmonic balancer. An impact wrench makes it easy. You will need a puller with metric screws to finish getting the balancer off. I've seen it mentioned that the tach won't work if the crank sensor is bad. That may not be true 100% of the time because it's a dual crank sensor.

Crank, ICM/Coils, and fuel pump are all posibilites as already stated.

To test:

ICM: remove (3 11mm bolts, 1 7mm bolt) and take to Autozone. Have them test it several times as it may need to heat up to fail.

Coils: As stated above, use the extra plug and check for spark.

Fuel Pump: As stated, use a fuel pressure gauge.

Crank sensor: After the car has heated up and gets ready to die, dump a bucket of cold water onto the sensor (located behind the harmonic balancer). If engine doesn't stall, the that is your problem. You could also try this after the car has stalled. If it starts up right after (without the 15 minute cooling time) then that also proves it is at fault.

Dont think a ignition coil is the problem.. usually just runs rough on that, but Im a believer in checking the easy stuff first.

Make sure fuel isnt the problem run some high octane through it but it doesnt sound exactly like fuel. My fuel problems usually related to ambient temperatures. Car would stall with bad gas when the ambient was above 95 degrees. What a pain that one was to troubleshoot. Not sure how it does it but guessing maybe a knock sensor may retard the timing so far out it stalls.

There was once when I changed the ignition module under the coils and thought I fixed it. Apparently the electronics in the newer module sensed a little better the weak signals for a while but eventually the problem returned.

CRANKshaft sensor has TDC and timing tracks for fuel and firing. Thus such a absolute stop of engine. CAMshaft sensor is for advance timing circuit and uses the same ground wires as the Crankshaft sensor to the Ignition Module.

Mine would jerk or just die on the road only and not parked running. If I remember right the spedometer would start jumping a little before the failure. Dont really know why.

I equate the sensors to the old HEI distributors but now the added sensors are on the balancer and help fuel consumption fine tuning of the PCM brain.

Dont quote me but I dont think its really a harmonic balancer anymore, more like a flywheel.

Previous posts of cooling it off are good ones.. Ive had opportunity to run a waterhose on that area to diagnose it or carry a gallon of water with a spout or hose.

Its a rather popular failure with a difficult troubleshoot for a newbie. My codes often wrongfully pointed to camshaft sensor. :banghead:

Oh yah. if you plan to do it yourself.. I had to toss my Wimpact Wench (china) with a good one to do the job.

Sounds like Ive had several problems with the same car.. but actually I revived a couple cars after getting them cheap.

Good luck

when it dies and wont start do the electric windows stop working?
If so the "hot" connecting plate that supplys the hot wire to fuel pump windows and like 5 other sources . it is on driver side floor and could be corroded or loose this is wrapped and needs to be rewrapped after fixing.
it is under the panel that holds the carpet down.
95 bonn my syptoms = stall sometimes, then more like every 20 minutes and would crank but not turn over, would start after 10 min and some times not!
noticed no power windows.
that was december and no problems since.
think melting snow and wet feet on floor corroded the connection for mine
found pic here same connection http://www.automotiveforums.com/vbulletin/showthread.php?t=599636