92 LeSabre won't start when hot...

[alleyoop49]

My '92 LeSabre starts fine when cold, but after running it for a while and heating the engine up- it won't start. I tried jumping a spark from a plug and got no spark. Once the car is started, you can run it all day and it runs fine until you shut it off. Then you have to wait on the engine to cool again to get it to start. Any ideas?

[gbeeley]

Probably crankshaft position sensor - this is a common problem on these cars! Happened to my '91 about five months ago.

[alleyoop49]

Thanks qbeeley! But do you think the engine would continue to run if it is the crankshaft position sensor that has gone bad?

[gbeeley]

Yes and no. It seems that the pattern is that these sensors don't fail outright. When mine went bad, the first real symptom was that I could not re-start the car after stopping in a parking lot. It would sometimes cause the car to stall, but typically it would make me wait about 20 minutes before the car would re-start after stopping. It would not set a trouble code unless it caused the car to stall (no code on a no-start).

It seems the part is affected by heat - and when you stop the engine, things around the engine actually heat up a bit before cooling off. I've seen that explanation from folks here on this forum.

Complicating and adding to the heat issue, the other theory I had was that the sensor takes a regulated 10V power supply from the system, and during cranking, the battery voltage can easily drop enough to cause that 10V to drop a small bit, thus a difference in sensor behavior during cranking. Sounds like the semiconductor device in the crank sensor just degrades over time.

There could be other causes, but what you describe matches what so many people have had happen w/ the crank sensor

- GB

[alleyoop49]

Makes sense to me...Thanks again!

[alleyoop49]

GB,
Just wanted to let you know---
I put a new crankshaft position sensor in and it solved my problem!
Thanks for all your help!!!
alley