Unknown ignition issue

kyearber

My dad has a 1992 Buick LeSabre, about a month ago it started to die after running about 10 mins or so. My uncle (a mechanic) replaced the crank sensor and thought he had it. It did it again so after working on it we all figured the ECM (the pad the coils sit on) was bad so a new one was put on. It will start and run for about 5-10 mins then shut down & will not restart until it cools off. We are at a lose here, my uncle has never seen anything like this. When it dies it gives no warnings, it just shuts down like you turn the key of, no spark at the coils, acc's work, no security light comes on or even flashes the engine will crank but does not even try to start. Any help would be appreciated.

Thanks

kyearber

I forgot to mention that the car has 150K miles on it. We also switched out all three coils with no effect. Could the crank sensor be over heating, it is brand new but I have bought parts that were defective before. It will start fine and run great when cold. But when it warms up it will just shut off and not restart until it cools off for about 15-20 mins.

imidazol97

Without diagnosis tools you have to do some guessing. Keep the fuel pump in mind. Even though you said it shuts off like a switch, it's possibly the fuel pump -- since you didn't say it have been replaced. When it dies, and you turn the key OFF and back to ON, do you hear the fuel pump run for 2 seconds or so? Everything else in the car turned off, you should be able to hear the hum. No fuel pump running, then check the relay for it to be sure it is not overheating and failing consistently.

As for the CPS that you already replaced, have some cold ice water handy and pour it over the CPS when the car shuts off. That cools it quickly and might put it back in operation. BUT, I'm going on memory, I think the CPS in the 92 had to be set with a gauge for the right clearance when it's installed. 93 and later had something that puts them into the right position. Is it possible your CPS is just out of adjustment?

Next, have you done the sparkplug test where you take the spark plug wire off when it won't start and put an old plug in it and laid it on the engine metal while someone cranks the engine. Do you get a good spark across the plug? If no spark, then you are back to something in the circuit from the CPS, spark control module, that's not getting a signal.

While it's cranking, do you get the injectors firing. I'm told you can feel the injectors open by touch while cranking. People also have taken off the electrical connector to an injector and put the two wires on the end of a 194 type light bulb, the little market light or dash light bulbs, into the connection and it will blink when the injector is fired by the computer. It's possible there's some failure in the computer, but they're usually not that consistent and often give erratic other problems.

One not mentioned is that you might have an ignition switch where the contact is worn and aged. Or the plastic housing connector at the switch is damaged from heat and the metal connector is pulling away from the contact with heat. The current through it with the engine running is heating up and it's losing contact. This is the switch which is on top of the steering column under the dash area--NOT the ignition lock cylinder or key cylinder.

The engine electrical diagram that includes the igntion switch is available from bbbind.com.
Technical specifications in middle of page, then TSBs and Wiring Diagrams. Pick wiring diagrams,
give your name and email, and then you can search for the diagram. This gives the wires and colors that
are carrying the power to several fuses which then send power to the various pieces running the electrical
parts on the engine.

kyearber

Thanks for the response. We found that when the engine shuts off there is no spark from the coils. I have a spark tester that I bought when my 97 Bonneville had ignition problems. The coils will not fire until the engine cools down and the engine will start fine. We checked for power at the injectors and they do have power coming to them (we'll try to see if they are working while cranking the engine when it repeats the problem which only takes about 5 mins). But without the coils firing I don't think the injectors are getting the signal to fire. I am leaning heavily towards the crank sensor, if it is out of adjustment could it cause this issue? Then again it might just be a defective part as well. One more question, the gauge used for positioning the crank sensor, can you use a standard feeler gauge? I've never seen one but I'll look for one at the parts store.

imidazol97

I cannot find a post now that talks about needing to set the position of the sensor on the 1992. I do see the 1992 and earlier cps is a different part number from the 1993 and later ones for leSabre. If it requires setting the position, there should be a paper in the package with one that tells what needs to be done. Might ask a parts place to let you look at a 1992 sensor to see if they include instructions.

Also, I read about a relearn procedure. You might try googling for the relearn procedure after replacing the CPS.

kyearber

I'm not sure the "relearn" applies to my dads car being a 92 (I don't think it is that smart, lol) but I'll check in to it.
Thanks
And I'll post any progress.

imidazol97

I rechecked and only the newer series had a relearn.

kyearber

Lol, ok, thanks again

kyearber

Update:
I started the car and waited for it to shut down. I noticed that the engine stumbled a couple of times then shut down, no warning lights of any kind. I checked the injectors and they are not firing either. I tried the cold water on the crank sensor and it did seem to start back up sooner. What would happen if the crank sensor was out of adjustment, could that cause the problem we are having? Is there a site I can go to that will show me more information on the gap needed around the crank sensor?
Thanks

imidazol97

Here's a video for a 1992 Regal talking about installing and spacing the CPS. Around 16 min is that part.
He does it without giving specifics of recommended ways.

Somewhere I have links for a sophisticated set of checks for the signals coming from the CPS to the
spark control module. If I can find it bookmarked in my old browser favorites, I'll post it.

kyearber

Ok, thanks I'll watch for it and I will watch the video

imidazol97

If you have a simple voltmeter this may help.

http://troubleshootmyvehicle.com/gm/3.8L/how-to-test-the-crank-sensor-1

bluebomber4984

Ok...I have a 91 Buick lesabre custom. When I started working on it, it just wouldn't crank unless I jumped it off. I changed the battery, had the alternator tested,  changed the plugs, wires, coil pack, ignition control module, starter, crank shaft sensor and fuel pump. Now it will turn over but will not start...what could I be missing?