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'78 350 - no spark??????

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 90K5, May 16, 2001.

  1. 90K5

    90K5 1/2 ton status

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    \'78 350 - no spark??????

    I'm fixing this guy's truck, and can't get it to spark. The ignition module is fine, and so is the coil. I replaced it yesterday. All the electrics are hooked up to the coil, but it wont spark. Any ideas?

    90K5

    See my truck at <A target="_blank" HREF=http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502>http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502</A>
     
  2. smp

    smp 1/2 ton status

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    Re: \'78 350 - no spark??????

    Did you check the fuse ? I blew mine when i had the key on for some tunes and was messing with the coil i grounded the hot wire took me a few minutes to figure out why i had no spark.


    <A target="_blank" HREF=http://WWW.SMP.COLORADOK5.COM>http://WWW.SMP.COLORADOK5.COM</A>
     
  3. 90K5

    90K5 1/2 ton status

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    Re: \'78 350 - no spark??????

    OK - there's no current to the distributor. There is a wire that is supposed to go to the fuse box in the spot that says IGN, but there is no wire there, so I'm thinking thats the problem[​IMG] Can't find the wire though. Anyone know where it comes from or what color it is? A wiring diagram would be helpful, but I can't find one. thanks

    90K5

    See my truck at <A target="_blank" HREF=http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502>http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502</A>
     
  4. CaptCrunch

    CaptCrunch 1/2 ton status

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    Re: \'78 350 - no spark??????

    Sorry dude... that is for aftermarket hook ups. Check the ecm or computer fuse... also make sure you are checking for power at the distributor while cranking or the key turned? No go then next shift it into nuetral and try again...if it starts it is the nuetral safty switch... otherwise you're going to have to drop the steering coulumn down and inspect the wires for breaks and see if there is power at the ignition switch. Good luck!

    [​IMG]
    1987 Chevy K5 Blazer- 350 TBI
     
  5. CaptCrunch

    CaptCrunch 1/2 ton status

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    Re: \'78 350 - no spark??????

    I suppose I shouldn't send out a wild goose chase w/out cause... does the truck crank over at all? Do you turn the key and get nothing? or do get it to crank over, but still no spark? Or does it just thud or click?

    [​IMG]
    1987 Chevy K5 Blazer- 350 TBI
     
  6. K5Jimmy

    K5Jimmy 1/2 ton status

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    Re: \'78 350 - no spark??????

    The question I would ask is....did it spark before you started fixing it?....if it did, then most likely it's something you changed/unplugged/disconnected or moved out of the way....walk away from it for a few minutes, and then retrace your steps....I wouldn't go rippin' into the dang steering column just yet....I'm gonna guess you are just overlooking something fairly simple....JD

    I'm at 10th and Plum....10 miles from nowhere, and Plum out in the sticks....Stuck?...Hell no..I still got some gas left..
     
  7. 90K5

    90K5 1/2 ton status

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    Re: \'78 350 - no spark??????

    The starter was turning over, but I killed the battery. Its recharging now. The guy actually driving home from having the starter replaced and got aobut 100 ft. Then the truck died, becase it ran out of gas. I towed him to my house and told him I'd fix it because I thought it would be coil or module=easy money[​IMG] Any wires I've moved I have put back, so everything is pretty much the way I got it. I'll try the neutral safety switch, hopefully thats the problem. Thanks

    90K5

    See my truck at <A target="_blank" HREF=http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502>http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502</A>
     
  8. smp

    smp 1/2 ton status

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    Re: \'78 350 - no spark??????

    The power wire to an HEI coil is pink and the ground (tach) is purple. If the nuetral safty switch isn't hooked up it won't let it crank at all (inless you bypass it and then it will crank in any gear)


    <A target="_blank" HREF=http://WWW.SMP.COLORADOK5.COM>http://WWW.SMP.COLORADOK5.COM</A>
     
  9. CaptCrunch

    CaptCrunch 1/2 ton status

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    Re: \'78 350 - no spark??????

    If it turns over it isn't the ign switch or nutral safety switch. So how do you know it doesn't have spark? do you have a spark tester? Next question is if it died cause it ran out of gas... where the heck did this no spark thing all start? If this a fuel injected rig and it ran outta gas he may/probably has fried the fuel pump. Use a test light and make sure you have power going into the coil/distributor. If you have done it all right then you have a problem in the distributor... check to see if the rotor is spinnig when you crank it.

    [​IMG]
    1987 Chevy K5 Blazer- 350 TBI
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: \'78 350 - no spark??????

    Modules are notoriously poor when purchased aftermarket. If everything else (easy stuff lol) is ruled out, you may want to try another module. Seriously, there is a HUGE problem with aftermarket (read Taiwan) modules not working even when new.

    Dorian
    My tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
    No anti-theft measures on your truck? No pity when its stolen
     
  11. 90K5

    90K5 1/2 ton status

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    Re: \'78 350 - no spark??????

    It5 did die because it ran out of gas, but I put gas in it, and now there is no psark. I checked by pulling out the park plug wire and looking into it to see if there is a spark. It will also shock you - past experinece - no spark, no shock. This is a '78, so its carbed, and gas is getting to the carb. I tested the pink wire yesterday, and there was no current to it, so I think the problem is a fuse or a fusible link. Any ideas where to look for these, except for the fuse box, i figured that one out[​IMG]

    90K5

    See my truck at <A target="_blank" HREF=http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502>http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502</A>
     
  12. 90K5

    90K5 1/2 ton status

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    Re: \'78 350 - no spark??????

    The rotor turns when I crank it, and as it turns out, my test light was burned out. I replaced the module, even though it was checked for continuity, I wasn't sure how it wazs doing under load. It still cranks, but no start. Does anyone know exactly what wires I need to trace to look for a fusible link, etc? Thanks

    90K5

    See my truck at <A target="_blank" HREF=http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502>http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502</A>
     
  13. 90K5

    90K5 1/2 ton status

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    Re: \'78 350 - no spark??????

    Where do the wires go once they plug into the distributor? The pink one is fine, I traced it all the way from the fuse box to the dist, and no problems with it. I want to kick this truck's ass!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

    90K5

    See my truck at <A target="_blank" HREF=http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502>http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502</A>
     
  14. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: \'78 350 - no spark??????

    Yeah you only really need the one pink (or is it red) wire going to the dist if its a '78. Tach would be the other plug in. Think the "hot" wire has a white connector on it.

    I wouldn't worry about fusible links. The fusible links control ALL power to the fuse box, if they are bad, you have no power, or intermittent if you are lucky. Its not them.

    No spark it has to be int he dist. IMO, unless teh pink wire jsut isn't getting voltage. I believe it has voltage any time the key is in the start or run positions.



    Dorian
    My tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
    No anti-theft measures on your truck? No pity when its stolen
     
  15. 90K5

    90K5 1/2 ton status

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    Re: \'78 350 - no spark??????

    What else could be wrong in the dist? Don't want to saoud stupid, but I've never worked on one except for coil, module, cap and rotor.

    90K5

    See my truck at <A target="_blank" HREF=http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502>http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502</A>
     
  16. 90K5

    90K5 1/2 ton status

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    Re: \'78 350 - no spark??????

    I think the pick-up coil is bad. I'm going to borrow two ohmmeters tomorrow to test it, but I think thats the problem.

    90K5

    See my truck at <A target="_blank" HREF=http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502>http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502</A>
     
  17. Triaged

    Triaged 1/2 ton status

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    Re: \'78 350 - no spark??????

    It could also be the pick-up coil. I think you test them for continuity but am not sure.

    '71 Blazer CST with alot of rust
     
  18. Triaged

    Triaged 1/2 ton status

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    Re: \'78 350 - no spark??????

    looks like you beat me to it

    '71 Blazer CST with alot of rust
     
  19. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: \'78 350 - no spark??????

    Let us know how it goes!

    Dorian
    My tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
    No anti-theft measures on your truck? No pity when its stolen
     
  20. 90K5

    90K5 1/2 ton status

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    Re: \'78 350 - no spark??????

    I will - just got home, I'm gonna look at it tomorrow, need to find 2 ohmmeters first though. Any suggestions on what to charge this guy? I've already replaced the coil, module, and have spent lots of time hunting through wires. I'm not really friends with hm or anything, so I'm not cutting him a deal on this.....plus his mom is paying for it. I'll see how hard it is, seems pretty straightforward though....

    90K5

    See my truck at <A target="_blank" HREF=http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502>http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502</A>
     

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