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91 Blazer - Cuts out/Stalls with Small amount of Throttle?????

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by swcblazer, Nov 18, 2001.

  1. swcblazer

    swcblazer Newbie

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    Here's more details... This problem does not come into play untill running in Stop and Go Traffic or SLOW Off-Road, if you are Driving normal (Gas and Go) you will Feel/Notice nothing.

    When you press the Throttle a small (I mean JUST a Little) amount it will start to Cut-Out and nearly die (It has died twice), as to move up a few feet in traffic from a stop. But if you let OFF the throttle and place in Neutral it will clear up and idle fine. It never idles bad or acts up in any way... Until you press the throttle to ease around... Also it Smells as if it's loading up when it does this, I pressed on the brake while in gear to force the problem without moving the truck and with the door open smelt it bad.

    I have replaced Spark Plugs and Air Cleaner... Had prob before and after.

    I have just been introduced to the TBI and need some help???

    THANKS... Steve

    ______________________________________

    Thanks... I'll Change the EGR first... Then Clean the TBI and Injectors... Also I'll look into that Code Reader (that sounds nice).

    I'll Post Results of the EGR change and so on.....

    Thanks to "everyone" again for the Info!
    STEVE
    <P ID="edit"><FONT class="small">Edited by swcblazer on 11/19/01 09:49 AM.</FONT></P>
     
  2. BorregoK5

    BorregoK5 1/2 ton status

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    In a carburated vehicle, this is usually a symptom of a faulty accellerator valve. This valve shoots a quick squirt of gas down the intake when you first open the primaries on the carb. Since carburators are vacuum feed, and opening a primary momentarily reduces vacuum, this squirt supplies the fuel needed until vacuum can take over and prevents a stall condition. Since your running TBI, perhaps this condition exisits as a result of a faulty sensor like the air flow meter or related electronics which don't catch the drop in vacuum or cant react in a timely manner to a sudden vacuum loss. Most Haynes or Chilton repair manual have a procedure for checking these components with a multimeter.

    I started with nothing and I still have most of that left! - <a target="_blank" href=http://www.echobit.com:81/k5/> Pictures</a>
     
  3. CV202

    CV202 1/2 ton status

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    First off, clean the throttle body out real good with carb cleaner (use the stuff rated for injection, as theres a coating inside the TBI that you want to keep) work the TB while spraying and the motor is running. Take it for a test drive. If it still does it, check the EGR valve. Press in on the diaphram in the base of it while its running (watch your fingers, it may be warm...) I believe the truck should approach stalling proportinate to how much you press...(Its been a while since I've messed w/one lol) If all else fails use your computer to your advantage. Ground out the appropriate contacts and see what codes you get. You should be able to find this, and a deinite on the EGR valve in a Chiltons or Haynes manual.

    Why do people keep calling it a Bronco!!!!! [​IMG]
     
  4. Twiz

    Twiz 1/2 ton status

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    Check,
    - Spray pattern from the TBI injectors, At idle, it should "flutter" (pulse width modualted) and be a light-to-solid cone shape.
    - Slowly increase throttle, opening by hand. Check for a "dead" spot (indicting possibly a faulty T.P.S.). The cone shape should take a solid form, and the fluttering should increase.
    - SES light on?
    - Check fuel pressure, (I don't think this is your problem, if there was a fuel pressure problem, it -should- starve for fuel on hard excell)
    - Check the Throttle Position sensor for a "dead" spot
    - Does the throttle shaft bind, wiggle or stick? (work by-hand, engine off)
    - M.A.P. sensor, and E.G.R.
    - Spark? Good plugs, wires, and cap? Distriputer shaft bearing worn?
    - Battery/chargeing sys, good voltage?

    Disclaimer:
    I have found it is very hard to diag. drivability problems over-the-net. So, I quit tring to. The above list is what I would check or are possibilitiys that I know of.
    Good luck with it.

    <font color=blue>Twiz</font color=blue>
     
  5. CaptCrunch

    CaptCrunch 1/2 ton status

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    LOL [​IMG] I like the disclaimer Twiz!! I found the same problem as well LOL.

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <a target="_blank" href=http://coloradok5.com/gallery/captcrunch>http://coloradok5.com/gallery/captcrunch</a>
     
  6. Philly87

    Philly87 1/2 ton status

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    A little info. My 87 TBI K5 does the exact same thing. I have replaced the cap, rotor, ignition module, throttle possition sensor, ESC sensor, and the sensor that controlls the EGR valve. None of these items fixed the problem. Although, the EGR valve has a vacume line that runs from it to the sensor that controls it. If I remove the vacume line from the EGR valve and plug it with a screw the problem goes away. Possibly a faulty EGR valve? I'm not sure. Haven't replaced it yet but it's pretty much the only thing left. Replacing the throttle position sensor did help a little but didn't solve the problem completely. I can hold my break and ease up on the throttle and my Blazer idles rough like it's got a lopey cam in it and it smells rich. It would die on me before I put the new TPS on. Hopefully this gives you some insight before you waste your money on sensors you don't need like I did. If you figure it out let me know, I'd love to solve this mystery myself. Good luck.

    Philip
     
  7. Eric78K5

    Eric78K5 1/2 ton status

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    Sounds like maybe a faulty EGR valve. Try disconnecting the vacuum line and plugging it, and see if the problem goes away.

    Eric78K5
    K5-Because Size Matters!
     
  8. BurbinOR

    BurbinOR 3/4 ton status

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    The guys gave great advice. Here's another good idea - buy a scanner (I use an Auto XRay 10110) and use it to monitor your key parameters. I recently found a faulty MAT (Manifold Temp Sensor) that upon startup showed my TPI motor intake temp at 180* [​IMG] and did not throw codes..........hmmm, no wonder it ran rough till it went closed loop! These scanners are about $150 at a Shucks/Kragen/Checker store and are very user friendly. Well worth the $$.

    Sounds like either your EGR or TPS, but as said above, hard to diagnose over the web...........

    <font color=blue>'79 ONE TON TPI K5 - See it at---&gt;<a target="_blank" href=http://www.blazzinor.rockcrawler.com>www.blazzinor.rockcrawler.com</a>
     

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