Ingnition spark is so weak - engine would not start.

I have 91' LeSabre. I have not been running it for a couple of weeks. Then, when I started it, at first it ran O.K. Couple of minutes later it began to run rough and then 2 miles later it died. The nex day I checked the spark (by sticking a screw driver in the spark plug whire) and the spark was so small that I could barely see it (I had to touch ground with my screwdriver to see it). Can anyone give me a hand and suggest what might cause it?
Thank you,
Alex

Well it sounds like its the ignition console(i just had this problem fixed yesterday). for a new one its like almost 200 but for a used one its arond 75 to a hundred + labor. Good luck with it mate.

Thanks Arshem. I will look into it ASAP and I will let you (and everyone else who is interested) know if it fixed the problem.

You may want to download any diagnostic codes in the ECM. The following link tells how to pull the computer codes off pre 1996 GM vehicles:

http://www.geocities.com/dann8785/serviceenginesoon.html

How you tested and got weak spark may be normal.
Notes on Electron ignition systems: These systems have one coil that is wired to two opposing cylinders (one on upstroke fuel laden intake cycle, one on upstroke exhaust cycle). They send spark to both cylinders at the same time, but only the fuel laden one actually sparks - this being electricity's path of least resistant. By testing for spark thru the wires (no fuel environment), spark may be equally split over the two cylinders appearing weak.

Seems like it shouldn't take much of a spark to ignite the fuel mixture in the cylinder, as long as it is getting fuel. Does it seem like it's getting gas? If so, maybe it's some sort of a timing problem due to a bad sensor.

Hello again!
I checked diagnostic codes and I got 39 which has to do with Torque Converter Clutch but I don`t think it is a sourse of the problem. I did take off Ignition console (3 coil unit where the spark plug wires come from). When I pulled it apart I saw some light green gooee stuff. I appeared that half of it was melted and dripped on the radiator hose. Could it be a proof that Ignition Console got overheated (couple of weeks ago the car did get overheated) and broke?
BTW, I did check fuel pump - it works.
Thanks,
Alex.

It seems to me that its a good possibility...I'd check into it, and if your mechanically inclined, its not to hard to replace.

I am mechanically inclined, but I know more about older kind of engines (the ones with destributor, points, and single coil) than the ones with ECM (what exactly does it stand for?) and multiple sensors. I will wait for some more feedback before I buy anything.
Thanks everyone for your time and willingness to help.
Alex

ECM - Engine Control Module = the computer.

Modern Computer controlled ignition systems:

The spark to each cylinder is controlled by the computer(ECM) using one or two sensors. All systems use a Crankshaft Position Sensor (CPS). This is used as a timing signal for number one cylinder and used in determining the engine speed (rpms). A second timing signal is generated from either a Hall Effect distributor or a Camshaft Position Sensor (electronic ignitions systems). The computer must see both signals in order to send a signal to the coil (or coil pack module) in order to send spark to the cyclinder. A problem in either signal typically results in a catch-all malfunction code of "no timing".

A Hall Effect distributor has a rotor and has lobes with magnetized tips instead of cam lobes. As the lobes pass a stationary magnetic pickup sensor, a timing signal is produced that the computer senses. These systems typically use a single high voltage coil for all cylinders.
An electronic ignition system module, have a multi coil pack in the ignition unit. Each coil in the pack is wired to two opposing cylinders (one on a compression stroke, the opposing one on an exhaust stroke). The ECM uses the Camshaft Position Sensor signal to control the electronic ignition module. In many electronic ignition systems, a single signal is used to run two cyclinders. When the coil discharges, electricity will take the path of least resistance. The cylinder on the upstroke with the compressed air-fuel mixture fires rather than the cyclinder on the upstroke exhaust cycle.

The timing advance function is controlled by the computer. It always tries to get the best performance, but is controlled by the oxygen sensors and a knock sensor.

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Notes:
a. You don't seem to be getting a code 11 (no timing) which means the timing sensors seem to be working.
b. You might want to check into obtaining a replacement electronic ignition module at a junkyard. Melting does not sound normal.

Thank you very much for detailed explanation - usual repair manuals on cars do not tell you all of that. I think I understand now how this part works now. I checked with Autozone and coil pack was about $46 but the Ignition Control module was $90. So I am going to find one at the junk yard tonight and I will let you know if that was the propblem or not.
Thanks again for your time.

I think I would verify that the fuel pump is working first, before buying an ignition module. Could be the pump died and the fuel pressure just dropped off. Seems like 4 of the cylinders would try to fire if you had one bad coil pack. Not likely that all would go bad at the same time. I had an 86 Oldsmobile years ago. I think when the ignition module failed on it, it gave me a code. There's no code here for the ignition module.

hey I have three ideas for you to try you will have 3 wires to the primary side of your coil take off the connector make sure you have around 12-13 volts to one 0 volts to your earth ground, and with someone turning the car over the other wire should have an interrupted(on-off) 11-12 volts. If that test good take an olm meter and take where you unpluged wire. on the back side of the coil and mesure resistance you should have like 10-15 olms of resistance on 2 of the connections. Then take on of the two what had resistance and take the other leed to the coil wire and you should have 3-4.5 kilolms of resistance.

I want to thank everyone who helped me to fix my problem with the car. I bought at the local salvage yard used Ignition Console (Ignition Control Module and Coils together) for $50 (I live near Sulphur Springs, TX). After I istalled it on the engine it started rightaway! Halleluia! I do appreciate all your isides into the world of automatic electronic ignition. You, guys, are awesome! Thanks,
Alex O.

oooops, one more thing... Now my engine idles kind of ruff. It seems like timeing is off. I changed spark plugs and whires and it drives fine on the road but when it idles it is shaky and when I add some throttle it chokes a little for a second or so. Does anybody knows what can help it?
Alex

Rough idle: The obvious causes are worn plugs or a bad wire. You should also check the battery cables for corrosion buildup. These buicks are known to get the yips when these isn't a nice clean contact to the battery. Also, on older cars in general, you should use a can of carberator clean and spray it all inside and through the throttle body. Oily, carbon deposits buildup from the PCV valve restricting airflow. They can gum up the small idle ports in the throttle body impeding the IAC and leading to occational misfires.

Thanks yogy for your help. I sprayed some around and in the air intake, but it did not help really. I will add injector cleaner to my gas and run it for some time. I have another question - my speedometer does not work. What is usual reason for that problem and how can I fix it?
Thanks, Alex O.

I finally fixed it! The used ingnition module I bought at the salvage yard did not work right. It would feed only 4 cylinders (2 were dead). That explains rough idle and shaking during normal drive. I went back to that salvage place and they replaced it for me. Other one finally worked! Now this baby works perfect. Thanks all of you for your time and valuable info. God bless.
Alex