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No Start - Tach Filter

5223 Views 6 Replies 4 Participants Last post by  vetteoz
I thought I'd take the time to share this. Friday afternoon I had a no start condition, no spark, and the injectors were not firing. I've noticed recently an occasional stumble and slight power loss, but nothing that could not be attributed it being a crossfire. Also starting a few weeks ago in the morning my tach would jump and read zero for a few miles then come back and function normally the rest of the day. Everything pointed to the ICM (Ignition Control Module), I've been through a few and noticed the symptoms of one on the verge of failure - oh and I carry one with all the time. Any way, I swapped out the ICM and still no spark, I had power everywhere, but apparently still no trigger signal. Remembering my previous tach problem, I disconnected the tach wire from the distributor cap, I turned the key and she fired up. I found this interesting, so I shut it down reconnected the tach and she again fired up. So I left it like it was and went about my evening. The next morning the no start was back. I disconnected the tach and again she fired right up. This time I decided to leave it disconnected. Upon driving I found that the power loss was more significant than I realized, I was surprised at how much power I had been missing. My only conclusion is that the tach signal has been shorting out causing the tach to read intermittently and reduce the intensity of the spark at the plugs, or causing other erratic behavior within the ECM. My hope is that the tach filter is shorting internally and it is the cause of these issues. I'm ordering a filter today and let everyone know the outcome. Until then I'm happily driving tachless.
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Fuel pump has been upgraded, have not bumped the pressure yet - maybe later. I did find a bad crimp splice, just the one that provides power to everything. I Cut it out and replaced it with a soldered spliced. Car runs much better when it has electrical power to consume... Still have not replaced the tach filter.
Could also be the wiring through the filter to the tacho shorting out.
Not uncommon for the insulation on the wires to break down , especially on a component mounted on the back of the engine in the heat
Good thought I'll check it out. After I fixed the splice I reconnected the tach and all seemed okay for a day, then she started running crappy again. I unplugged the tach trigger from the distributor and all is well again. I need to get off my lazy @$$ and replace the filter & check the wiring while I'm at it.
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