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4 wire harness coming out of distributer?

Discussion in 'The Garage' started by bryguy00b, Oct 13, 2002.

  1. bryguy00b

    bryguy00b 3/4 ton status

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    my dad wants to know what it is..he doesnt know...and he says its not on his 79...
     
  2. 4x4k20

    4x4k20 1/2 ton status

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    it goes to the computer your 84 has a knock sensor on the bottm rt side of the engine rite above the starter you can take that dist. out and replace it with an older one and get rid of the computer unless you have to have emmissions
     
  3. bryguy00b

    bryguy00b 3/4 ton status

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    would this have anything to do with my blazer not starting? it will crank over but it will not start. and do you mean replace the distributer with an older one?
     
  4. 4x4k20

    4x4k20 1/2 ton status

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    yes you should check the 4 wire connector where it comes out of the firewall to see if it has fire on 1 of them when you cut on the switch if it doesnt check your fuses or you can do what i did i had a old dist out of a 79 i put it in and done away with the computer there is an old post on here somewhere that shows how to by pass the computer ill see if i can find it and let you know it had pictures with it
     
  5. bryguy00b

    bryguy00b 3/4 ton status

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    when you cut on the switch? what do you mean..sorry for the dumb questions but i think we may have something hear..
     
  6. 4x4k20

    4x4k20 1/2 ton status

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    i found the post go to my profile and under show all user post click on it its about the fifth page
     
  7. bryguy00b

    bryguy00b 3/4 ton status

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    thanx!! im printing it out right now to give to my dad..
     
  8. bryguy00b

    bryguy00b 3/4 ton status

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    ok well i got more questions becuase this isnt really adding up. we have at least 7 volts while cranking the engine..we are getting enough power that way, thats why we dont get it that it will not start. and does the pink wire that feeds the computer come from the fuse block? was this feed shorting the battery feed to the distributer?

    thanx
     
  9. u2slow

    u2slow 1/2 ton status

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    That 4-wire distributor does not have a vacuum advance, right?

    I was under the impression that the computer, knock-sensor, distributor, and carburetor (special feedback type) all worked together.

    I would think if you ditched the distributor, you'd have to go back to a conventional carb too(?) /forums/images/graemlins/confused.gif
     
  10. bryguy00b

    bryguy00b 3/4 ton status

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    but i dont see a reason why i would need to do this..this engine ran great befor we swtiched it to this truck. now we hook everything back up and we cant get the f-er to start..it HAS to be something dumb...like a fuse or something..
     
  11. txbartman

    txbartman 1/2 ton status

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    On my 85, I replaced the HEI distributor that had the ESC (4-plug setup) with a non-ESC HEI from Summit. Runs like a charm. The computer on these models doesn't do much ecept advance the timing if knock is detected. I don't believe it does anything with the carb. The ESC computer is not the ECM that controls most motors.
     
  12. txbluethunder

    txbluethunder 1/2 ton status

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    actually the esc computer retards when it detects knock /forums/images/graemlins/tongue.gif. and the carb just has a temp sending unit connected to it so it can adjust the fuel depending on the temp of the coolant. heres the link to bypass the esc junk
     
  13. bryguy00b

    bryguy00b 3/4 ton status

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    well would any of this have anything to do with my truck not starting, thats really what im trying to get to the bottom of. if you read my post a couple posts up from this one...the one right befor this i beileve..does any one know the answer to my pink wire question...and the reason my truck will not start? does this computer have any reason to keep my truck from starting if i have over 7 volts when i crank the engine..which is enough to do it i guess form the book. my dad is working on my truck, i dont know enough about this stuff to do it so im passing the good info from you guys along to him..thanx for the help so far!!
     
  14. bryguy00b

    bryguy00b 3/4 ton status

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    did you have to take the computer out to? ir did you just switch distributers and leave it in there unhooked or something...i just want my truck to run!!! /forums/images/graemlins/frown.gif
     
  15. txbluethunder

    txbluethunder 1/2 ton status

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    from previously posted link:

    "There is a power feed to the spark control unit under the dash that comes off of the pink (hot) wire to the distributor. The pink wire clips into the connector for the feed, which in turn clips into the dist. cap. What had happened was the feed for the Spark Control was shorting out somewhere, killing the spark. I talked to some Chevy mechanics at my dealer about this and they told me how to bypass the spark control computer and keep the original distributor, something they claim is done quite often."

    yes...if the electric spark control computer is disconnected you engine will not start. but you could do this:

    Here is a way to remove the ESC from the distributor without having to change distributors. I recently found this quick fix on the 73-87 truck forum at Chevytalk. It was posted by a member that goes by the name of 86Scottsdale.


    I had a problem with my 86 C20 305-H engine. It could start and run fine and just suddenly die out, sometimes start right back up or take a couple hours to get restarted. After several weeks of this nonsense (and getting very good at getting those half turn dist. cap latches off), I did some checking. There is a power feed to the spark control unit under the dash that comes off of the pink (hot) wire to the distributor. The pink wire clips into the connector for the feed, which in turn clips into the dist. cap. What had happened was the feed for the Spark Control was shorting out somewhere, killing the spark. I talked to some Chevy mechanics at my dealer about this and they told me how to bypass the spark control computer and keep the original distributor, something they claim is done quite often.
    First thing to do is unclip the spark control computer lead from the pink wire and just clip the pink wire directly to the dist. cap at the. Make sure you plug it into the cap at the BAT terminal. The second thing is to locate the 4 wire connector that feeds into the ignition module. There's a brown (D), green (C), white (B), and black (A) wire there. The letters in () are on the black clip that the wires come out of. You cut the green (C) and black (A) wires between this clip and where they go into the distributor. Then all you need to do is solder the 2 cut leads from the dist/ignition module together, i.e. the green and black ones, (make sure to tape the exposed wires) and now your HEI distributor will function just as a pre ESC model does. I did this and it has been running fine for well over a year now.

    Dan

    Note: Here is a photo I made of the plug which goes to the ESC control and feeds the ignition, which Dan mentioned above. I labeled the wires which need to be cut and showed which wires are A, B, C and D.
     
  16. bryguy00b

    bryguy00b 3/4 ton status

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    ahhh ok!! thanx that info was very usefull! thank you for the post!! same to everyone else! ill let you know if i got any more questions...thanx a lot!!
     

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