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Problem Child 1991 Cavalier won't start HELP


Air Race Addict
11-27-2012, 03:00 PM
New to the forum. Lots of great info here. I need help. I was driving to work, engine died on the highway. Wouldn't restart. No hint before it happened. I have replaced the crank sensor with no help, checked fuses, fuel pump is running on key to start until it pressurizes like normal, new spark plug wires this summer, only code is flashing 12 with a jumper between A/B, no obvious wiring issues. Now I have to get serious about troubleshooting. Does anyone have any hints about access to the ignition module/coil packs? It's an auto transmission if that's any help. It looks like the easiest (hardest :cwm27: ) access is to pull the intake manifold. I am an aircraft mechanic by trade and looking for a way to do this smarter, not harder. Thanks for any help in advance.

Tech II
11-27-2012, 05:07 PM
2.2 or 3.1?

I assume it cranks over but doesn't fire/start?

Like any engine, compression, spark and fuel.....

Have you checked for spark, with a spark tester, at the end of each wire?

If no spark, could be coil, ICM, crank sensor, etc.

If you have spark at all of them, need to check fuel pressure or spray carb cleaner into intake to see if it starts....

If it starts with carb cleaner, then you either don't have enough fuel pressure(power to pump[relay?], pump or plugged filter) or the injectors are not firing(check with noid light at harness to injectors.....if a 3.1, you can't do this at the injectors directly......you can check impedance or resistance of injectors at the external harness to the injectors....each injector is 12 ohms, but since 2-4-6 and 1-3-5 are in parallel, they will ohm out at 4 ohms per circuit....if much less than that, then one of them has shorted out.....when this happens, too much current flows through the injector driver in the ECM(computer), and the computer will shut all 3 injectors on that circuit down......if higher than 4 ohms, then one is open(reads 6 ohms) or 2 are open(12 ohms).....

If it doesn't start with carb cleaner(temps have to be higher than 40F, or if it's colder, the carb cleaner will condense in cold intake and not start), then a compression test has to be done(check condition of plugs when out.....fouled, carbonned, wet, etc.)....if no compression or low on all, it's possible it jumped time....

Air Race Addict
11-27-2012, 05:25 PM
2.2 or 3.1?

I assume it cranks over but doesn't fire/start?

Like any engine, compression, spark and fuel.....

Have you checked for spark, with a spark tester, at the end of each wire?

If no spark, could be coil, ICM, crank sensor, etc.

If you have spark at all of them, need to check fuel pressure or spray carb cleaner into intake to see if it starts....

If it starts with carb cleaner, then you either don't have enough fuel pressure(power to pump[relay?], pump or plugged filter) or the injectors are not firing(check with noid light at harness to injectors.....if a 3.1, you can't do this at the injectors directly......you can check impedance or resistance of injectors at the external harness to the injectors....each injector is 12 ohms, but since 2-4-6 and 1-3-5 are in parallel, they will ohm out at 4 ohms per circuit....if much less than that, then one of them has shorted out.....when this happens, too much current flows through the injector driver in the ECM(computer), and the computer will shut all 3 injectors on that circuit down......if higher than 4 ohms, then one is open(reads 6 ohms) or 2 are open(12 ohms).....

If it doesn't start with carb cleaner(temps have to be higher than 40F, or if it's colder, the carb cleaner will condense in cold intake and not start), then a compression test has to be done(check condition of plugs when out.....fouled, carbonned, wet, etc.)....if no compression or low on all, it's possible it jumped time....
Thanks for the reply. It's a 2.2. We checked for spark, no spark, (Air Temp was about 28 F). We tried starting fluid, nothing. Put in a new crank sensor, nothing. With key to on, Fuel pump is running until pressurized then shuts off, like it's supposed to. Trying to find out if it's possible to get to the ICM/Coil Packs without removing the intake manifold. I replaced the plugs and wires in May.

Air Race Addict
11-28-2012, 01:22 PM
I am getting fuel to the throttle body. No spark. I checked 3 and 4 to cover both coil packs. So, bad ground somewhere? ANyone know where the ground for ICM terminates?

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