1990 LeSabre won't start!!!

[dapopes]

My Buick won't start after I come back from across town or 60 mi. trip. There is NO fire,until it sits for about 3 hours! Then it starts and runs great, until I shut it off again. Computer is good, coil pack and module is good. Does anyone have an idea? Crank sensor? Cam sensor? Is that a common symptom?

[Alibi]

Any troble codes? If not, then I suspect that your crank sensor is faulty and fails at operating temps.

[dapopes]

Thanks for the reply Alibi! Is the crank sensor easy enough for a "shade tree" mech. like me to replace? I can rent the harmonic ballancer puller, but I don't know if they rent the "special tool" needed for the sensor install! I' see tommorow. So is PERFECTION real important in this proceedure? Thanks

[dapopes]

By the way,someone told me that unplugging the sensor would tell me if the crank sensor is the problem...true or false?

[Alibi]

It is a pretty do-able situation. However, you need to do a forum search on the harmonic balancer and read through some of them threads, especially those specifig to the HB. Basically, you need either a 1inch impact wrench (huge!), a really long breaker bar, or a stout bar attached to the bolt and then crank the engine over enough for the bar to catch on the frame and break the bolt loose.

The part itself is about $30, it comes with a frame and the sensor itself that slides into the fram and is then screwed down after it is adjusted. As far as adjusting it, you need to slide the harmonic balancer over the whole assembly and wiggle the sensor in the frame untill the balancer can rotate without hitting any of the splines on the sensor. So no, perfection isn't required but you definately need to spend some time getting it lined up right.

Forum searches are a good thing to go through since this is a common problem.

You may want to wait to go out and buy parts until we get a couple more people to either agree or give suggestions of parts that are easier to swap out than a crank sensor.

Oh, and as for unpluggin it...It might work but by unplugging it all you would be able to check would be if the engine acts the same way as it does now because unplugging it would simulate a faulty sensor and the computer would respond as such. If the engine runs significantly different, then I'd say that the crank is probably not the issue.

As far as other possibilites of your problem source I would have said your coil packs, but apparently you've alread replaced those (new ones I hope, junkyard electronics are risky).

[HotZ28]

The engine will not start or run with the crank sensor unplugged! The link below may give you some tips on how the system works.
regal 1-4 coil problem

[dapopes]

Thanks for the ideas Alibi! I didn't even check for codes(a mech said that often, crank sensor won't show up in test anyway!) I did try my sons mod and coil pack and it did the same thing(wouldn't start hot, but starts and runs great when cooloed down.) HotZ28 had a good idea trying the "headlight trick"! If I understand correctly, I am to atatch a 3 prong hallogen to the 3 blue wires on the module and then crank engine over to see if it flashes. Then do I try the yellow, blue and green wires next HotZ28? I assume I'm gonna want to do this while engine is hot and not starting right? Please excuse my....slowness!!!!