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ENGINE ??'s

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by KING K5, Dec 27, 2000.

  1. KING K5

    KING K5 1/2 ton status

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    ENGINE ??\'s

    Hey I was wondering if any of you could give me some ideas as to what's going on with my rig. I have an '81 K5 with 5.7L 350 w/Quadrajet carb.
    I went wheelin' the other day and did a still water crossing that was up to the middle of my exhaust pipes. Going in had no problems. on the way back however when I came out of the water my engine started running like it was miss firing or something. I got out and popped the hood, NO water in the engine compartment (I was going slow to not get water in there) . Let it run for a while and it ran well enough to get home but still a little rough. Pulled the distributor cap and cleaned out any possible condensation from the cap. It ran a little better but still rough. Next day went to work and still running a little rough then on the way home that night (last night) it was running rough when I started it then when I was accellerating onto the freeway my choke light came on and stayed on the whole way home. When I went to come to work this morning, the choke light once again stayed on and when I first went to drive it I noticed black smoke coming from the exhaust pipes. This black smoke went away about half way to work. Then when I stopped at work and put it into park I noticed it was idleing higher than normal then when I turned off the engine at it dieseled for a second then shut off, it's never dieseled on me before......any ideas? What the heck is going on with my truck?? I appreciate all help in advance!!
    Thanks!
    Jeff
     
  2. LittlePig

    LittlePig 1/2 ton status

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    Re: ENGINE ??\'s

    Offhand, I'd say some part of the engine management system is facked. Either the O2 sensor, or maybe some sensor up on the block hit by a transient current (if water temporarily created a short in yer electricals). Either way, it sounds like the engine doesn't know how it is running, and/or is getting confusing signals, and is compensating the best it can.Could also be water got into the fuel system somehow, and is fouling things up.

    Email: xiaozhu@my-deja.com
    ICQ: 84108805
     
  3. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Re: ENGINE ??\'s

    I don't think an 81 with a Quadrajet is managed by any sort of computer. It definitely doesn't have an O2 sensor[​IMG]
    I would suspect the problem may lie with the electric choke. When the truck is cold remove the air cleaner assembly and watch what the choke does as the truck warms up. The choke plate should open within a few minutes of initial start-up. If not then check the wire going to the choke, it should have 12 volts going to it whenever the key is on. Also check that the choke plate and related linkages all move freely, sometimes these get sticky and will cause the choke to hang up.

    Rene

    [​IMG]
     
  4. mudhog

    mudhog THEGAME Staff Member Super Moderator

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    Re: ENGINE ??\'s

    trusty is right there is no computer on an 81. i would check more into the choke area

    s.smith 77blazer lookin 4 mud
     
  5. TX Mudder

    TX Mudder 1/2 ton status

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    Re: ENGINE ??\'s

    It sounds like your electric choke.
    -- Mike
     
  6. KING K5

    KING K5 1/2 ton status

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    Re: ENGINE ??\'s

    I'll check that, and to let you all know, No I don't have any computer on my engine but I do have something called ELECTRONIC SPARK CONTROL, Anybody familiar with this and could this be causing the problem??? If so, how do I check/test it?? Thanks for the replies so far!!
    Jeff
     
  7. Butch

    Butch 1/2 ton status

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    Re: ENGINE ??\'s

    Electronic spark control has to do with your distributor. I would stick with the electric choke theory, although if your distributor did have any condensation in it you should spray the inside of it with WD-40 to get rid of it.

    I thought I was wrong once,
    but I was mistaken
     
  8. bart

    bart Registered Member

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    Re: ENGINE ??\'s

    You may want to change the HEI distributor ignition module...inside the cap, it bolts to the bottom of the distributor housing...it is about 3 to 4" long and has plugs on each end. I got mine a little wet and ran it, and it had severe driveability issues. ( you said you dried out the cap a little?) You may have gotten this wet enough to short it out...and cause it to be damaged.
    Other than that, there isn't much else other than a knock sensor that might be shorted...which would cause your electronic spark control ( i think they had this in 81) to retard the timing a lot...you can tell if you have ESC if the distributor has a 5-pin connector out of it that goes into the firewall on the passeger side...
    but i'd try the ignition module first.

    bart
     
  9. bart

    bart Registered Member

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    Re: ENGINE ??\'s

    oh, I see you say you have the ESC. well, I think if you just disconnect this plug at the firewall by the distributor, this will disable the esc from the ignition system.

    keep in mind, you should have +12 volts at the electric choke terminal with the key in the run position. Maybe check this first with a testlight or meter...if it never gets voltage, it never opens all the way. you may have popped a fuse (as was suggested by someone else)
    try the choke power check , then the esc test, then go for the ignition module...

    good luck

    bart
     

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