LT1-LT4 Modifications 1993-97 Gen II Small Block V8

no spark, any ideas?

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Old Oct 31, 2009 | 04:39 PM
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Default no spark, any ideas?

OK, first off I have to tell you that the previous owner did a pretty bad hatchet job on the wiring of this car. That said, I'll begin my story.

I ran out of gas the other day, thinking I had enough to get to the station. I didn't. I pushed the car to the station and put in $10 worth, but the car wouldn't start and I couldn't hear the pump prime so I figured I killed it. I sprayed a little starter fluid in the intake and it would run on that so I was confident I had a no fuel issue. I bought a replacement fuel pump and installed it. That's where things got wierd.

With the new fuel pump in I went to start the car, still won't start. I re-tested the pump and it's good so I started looking at the wiring. I found that there was no voltage to the pump, only to the gauge wire. I traced it back and found the wires in the fuel pump harness cut, the ground wire completly and the power wire mostly. I guess something must have bounced up under the car while I was dragging it back home. I spliced the wires back together and have power to the pump and fuel at the schrader valve so I know the fuel is good.

Still won't start, this time even on the starter fluid.

I bought a spark tester and have no spark now. I checked the wires at the ICM and there is no voltage on the A or D wire (the 2 middle ones). I also checked the fuse in slot 11 and it is fine. I think maybe I hit a harness with the strap I was towing with but I don't see one loose.

If the coil went bad, would it keep voltage from the connector on the ICM? Is there somewhere else I should check? I'm kind of at a loss here and want to get some advice before I tear into it chasing stuff I don't need to chase.

Thanks in advance for any help!
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Old Oct 31, 2009 | 05:30 PM
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What about the opti?
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Old Oct 31, 2009 | 05:46 PM
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9 times out of 10 its the opti trust me i've been through so many of them and gm opti's too....
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Old Nov 1, 2009 | 12:29 AM
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http://shbox.com/1/4th_gen_tech2.html#opti_test
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Old Nov 1, 2009 | 10:28 AM
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I'm normally the first guy saying to test the opti, but this time the voltage stops before the ICM so it's not even getting to the opti.
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Old Nov 1, 2009 | 06:46 PM
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Any other ideas? I saw a few posts on here from folks with the same problem but none of them posted a resolution.
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Old Nov 1, 2009 | 07:00 PM
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Not sure if you said it cranked over or not. But I'd still say try the opti lol.
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Old Nov 2, 2009 | 04:57 PM
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It does crank over, just won't start. I would check the opti if I was getting power to the ICM and coil and it still didn't start, but since I'm not getting any ignition power to the ICM at all I think it's somewhere else. i did have the opti off a couple of weeks ago and took it apart to inspect it. I put thread locker on the screws and checked the points. A little RTV on the seal and buttoned it back up. I'm confident it's good.

I'll get under the dash and see if I'm getting 12V ignition at the key, maybe a harness got unplugged or a wire got cut when we did the alarm last week. I told my friend not to use t-taps but you know some folks.......I'm thinking a t-tap that was too small or bent got squeezed on with pliers and maybe severed the wire. That's what I'm hoping anyway.
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Old Nov 2, 2009 | 09:19 PM
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remember optis break in different ways one time when my opti broke it didn't throw a code and then another time it did. it just seems easy to replace now for me so i usually look at it like its the first thing and it is always my problem
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Old Nov 2, 2009 | 09:37 PM
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Looks like we're on the same boat let me know what you find.
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Old Nov 3, 2009 | 02:22 AM
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You need to find out why ur not getting power to the icm first? Does ur coil even power up?
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Old Nov 3, 2009 | 08:15 AM
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There is no power to the wires going to the coil. Do these cars have an ignition relay somewhere under the dash? I checked shbox but found nothing about an ignition relay. I know there is not one under the hood.
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Old Nov 3, 2009 | 08:22 AM
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I had this similar problem and it turned out to be the Ignition Control Module.
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Old Nov 30, 2009 | 10:28 AM
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OK, I saw a lot of people with the same problem and no posted solutions so I'll close this out. I checked the ignition fuse several times with my meter and my test light, plus a visual inspection. In all my years of installing I have heard of fuses being bad and not looking like the were but had never seen it with my own eyes. I thought I should check it our anyway because fuses are free and as soon as I replaced it with a new fuse I had voltage where I needed it and the car fired right up.
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