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4.3L Vortec Getting a Rebuild

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Old May 16, 2022 | 10:09 PM
  #251  
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Thanks for checking Les, I think now we have narrowed in on the problem… How could I check for spark in the coil wire?
 
Old May 16, 2022 | 10:33 PM
  #252  
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Take a (old if you have it) spark plug wire and spark plug and plug directly into coil. Clamp spark plug to something metal with vice grips and watch for spark across electrode while cranking.
 
Old May 16, 2022 | 10:44 PM
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How about a video of the engine trying to run?
 
Old May 16, 2022 | 11:39 PM
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Thanks Les, I have old spark plugs and wires I can try this with tomorrow. I don’t really want to try starting the engine again until I at least try and fix what is going on as last time it wasn’t good at all with smoke coming from the intake. But next time I try firing it I will take a video for you guys.
 
Old May 17, 2022 | 02:16 PM
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If you are starting your engine with the throttle body open on top (no duct), you really should install the air cleaner ductwork. About the only thing bad that can happen with screwed up ignition timing is to backfire out the throttle body. Having the ductwork on prevents anything from catching on fire. Other than that, any pops and bangs and smoke is inconsequential to the health of your engine so please don't worry quite so much.
 
Old May 17, 2022 | 02:28 PM
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As for your scanner not reading RPM. I did turn the key on and made sure I was connected and could read coolant temp. Only then did I turn the key all the way to crank the engine and try to read RPM. Scanners need to establish communication with the PCM. Maybe you didnt give it enough time after key on before cranking? Might be worth another try.
 
Old May 17, 2022 | 02:29 PM
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Not trying to confuse things - just throwing out possibilities.
 
Old May 17, 2022 | 02:43 PM
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Thanks Les, when I tried starting it I did have the air cleaner ductwork hooked up. I can try starting it again when I get home in a few hours... Before I try starting it however I will check RPM while cranking again and I will also test the coil wire as you said. I think my results with the scanner reading RPM won't change as I had the truck on accessory and let the scanner connect first, then opened the live data menu and scrolled down to RPM, and cranked the engine. But it shouldn't hurt to try again and make sure I'm getting a reading from other sensors as well. Now I'm wondering if my crank sensor is not giving out any information, would my coil still fire just not at the right time? Or would it not fire at all?
 
Old May 17, 2022 | 05:23 PM
  #259  
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If crank sensor is dead - then no steady spark at the coil.

But unless there is some problem with the sensor install i'm still betting a problem with the distributor orientation. We will see. Please keep an open mind
 
Old May 17, 2022 | 05:29 PM
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Originally Posted by reway
Thanks Les, when I tried starting it I did have the air cleaner ductwork hooked up. I can try starting it again when I get home in a few hours... Before I try starting it however I will check RPM while cranking again and I will also test the coil wire as you said. I think my results with the scanner reading RPM won't change as I had the truck on accessory and let the scanner connect first, then opened the live data menu and scrolled down to RPM, and cranked the engine. But it shouldn't hurt to try again and make sure I'm getting a reading from other sensors as well. Now I'm wondering if my crank sensor is not giving out any information, would my coil still fire just not at the right time? Or would it not fire at all?
i wouldnt connect the scanner on accessory. Just turn the key on and connect. Dont cycle through the off position after connecting.
 



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