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87' S-10 2.5 issue

Discussion in 'Chevy S10 Forum (GMC Sonoma)' started by GearHead899, Sep 19, 2013.

  1. GearHead899

    GearHead899 New Member

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    hey guys. A buddy of mine just bought a 87 s10 2.5 4 speed with 88k original miles on it. We are having a problem that is stumping the hell out of us. Let me start from the beginning. We went to buy the truck. guy said it was sitting for a while but we started it and it started right up. didnt test drive it far, just around thew block but ran strong. Bought it and started driving it home and after about 15 minuted of driving i did notice it would sputter/ missfire at higher rpm (of course it doesnt have a tach so wasnt sure if it was just hitting limiter but seemed like more of a miss) so as soon as we pull onto the highway it starts cutting out, I tried to give it gas but nothing and as soon as i push the clutch in, it stalls out completely. tried to restart it and it fired up, got 10 feet and it did the same thing again. then it wouldnt re-start again. saw the injector pulsing fuel into the TB so i know it was getting fuel. So we got it towed home. as soon as we got it home it fired up again. We did a basic tune up as the plugs, wires, etc looked original. things we did so far; oil change, plugs, wires, cap, rotor, coil, coolant temp sensor (front one), removed cat (we were thinking it could be clogged). still does the same thing! fires up and runs fine when cold. can run it for about 10-15 minutes till it gets hot it seems, then it will start to missfire at high rpm and shortly after it will just cut out. and wont start and stay running again till it cools off. any ideas?? we are running out of ideas lol
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  2. BurbanMan

    BurbanMan Member

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    Check out the ignition module. Mine did the same thing. The ignition module would fail when it got hot. I've also had the map sensor do that to me on my dodge
    #2
  3. GearHead899

    GearHead899 New Member

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    well actually we just got a map sensor for it lol gonna throw that in it and see what happens. fingers crossed!
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  4. GearHead899

    GearHead899 New Member

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    Ok so the map sensor made no difference. i guess ignition module is next :confused: What if that doesnt fix it? i have no idea what else it could be lol its weird it will drive along just fine then randomly the gas pedal will go dead then it comes back to life. then shortly after it usually the gas pedal will stay dead and stall when i come to a stop and it wont re-start till its cold again
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  5. BurbanMan

    BurbanMan Member

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    Have you hooked a timing light to it out of curiosity?
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  6. rg79

    rg79 New Member

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    I agree with the ignition mod. You could also try the throttle position sensor.
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  7. BurbanMan

    BurbanMan Member

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    Are you getting fuel?! Change the fuel filter and see what happens. If it still dies, pop the air cleaner off and have someone turn the key while you look in the TBI. It should spray when they turn the key to the "on" position and when they crank it over after a second the fact that it starts after it's cooled off also makes me wonder if there's crap in the tank (maybe getting suck up to the strainer). After sitting for a while it's going back to the bottom of the tank resulting in the ability to start the truck. I would pull the tank regardless and clean it out if the truck has say for a long period of time before your purchase. This should give you a few avenues.
    #7
  8. E_HILLMAN

    E_HILLMAN New Member

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    maybe you have water in the fuel? My solution is to drain fuel and put new fuel in the truck. Then install a V8 and get on it!!! lol
    #8
  9. Pikey

    Pikey Moderator

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    x2 on the fuel filter. Also might want to check the egr valve.
    #9
  10. BurbanMan

    BurbanMan Member

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    Any updates?
    #10
  11. GearHead899

    GearHead899 New Member

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    sorry for my absence guys! turns out the issue was a bad ignition module. when i pulled the old one out i could see some corrosion on the prongs where the connector goes. ever since i replaced that it has been fine! WOOO! lol also we put on a new exhaust since it had none and was stupid loud. we just did a straight pipe off of the downpipe to a universal muffler we got online and did a side exit right behind the cab. still pretty loud but a ton better then what it was. My buddy also got bored and started rattle canning the exterior with primer (since it was about 10 different colors) so at least now its one color. will get some pics soon for you guys. Another question, my buddy wants to hook up a tack since there isnt one. how would we go about doing that on this truck?
    #11
  12. BurbanMan

    BurbanMan Member

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    The coil mounts to the top of the dizzy right? If so, you can get an accel tach install pigtail from the local autozone or oreillys to plug into it to make it all but plug and play

    Good to hear about the module
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  13. GearHead899

    GearHead899 New Member

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    the coil actually mounts like under the intake manifold. not sure if that will work :confused:
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  14. stchman

    stchman New Member

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    IIRC, the 2.5L in the old S-10s was the "iron duke".
    #14
  15. BurbanMan

    BurbanMan Member

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    Oh yeah. That's right. I'll do some homework and fin my wiring diagram for the 2.5 I used to have.

    Yes it is
    #15
  16. stchman

    stchman New Member

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    It was amazing that GM put that engine into a LOT of vehicles, including a Camaro!!!!

    The Iron Duke was a very sturdy engine, but it almost sounded like a diesel it rattled so badly.
    #16
  17. Conlan Rose

    Conlan Rose Super Moderator

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    It actually is the engine in most USPS Mail Trucks because they are built on a modified S-10 frame. Most of those trucks are all still on the road after 25+ years of use.
    #17
  18. BurbanMan

    BurbanMan Member

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    The green wire goes to te white wire coming off the ignition coil.
    #18
  19. GearHead899

    GearHead899 New Member

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    awesome! thanks man
    #19
  20. BurbanMan

    BurbanMan Member

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    anytime. I try
    #20

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