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Can't get to work!!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 89K5, Dec 6, 2000.

  1. 89K5

    89K5 1/2 ton status

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    Can\'t get to work!!

    Sorry this post is so long but I want to exhaust all my options before spending $500 bucks at a shop.

    My same old problem ,only worse. K5s been hesitating. This morning its so bad that it started stalling. Its only been happening when cold, but once warm its been fine. But Monday it bucked the whole way to work even once the engine warmed up. Tuesday the temp was around 30, ran fine once engine warmed up. Its about 18 degrees outside today and I drove around my neighborhood for 1/2 hour, engine got plenty warm, but kept wanting to stall. I've replaced the EGR(last March), fuel filter, plugs, rotor, wires(all in May), MAP sensor (Monday), Coolant temp sensor (Last night). HELP!!
    My wife just said she'll drop me off at work. When I get home I'm going to try the idle air valve (?). I heard about it on this site but not sure what to do. I see there are two lines entering the back of the TBI. Is one the gas line and one the IAR valve? Or is it not a line? Do I clean it, or clean and adjust? How do I adjust it?

    If its not that, where do I go next? Fuel pump? I didn't think it was the fuel pump because drop in rpm kind of has a rhythm to it and it would happen when warm too. But now its starting to happen constantly so...
    Thanks
     
  2. Blue85

    Blue85 Troll Premium Member

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    Re: Can\'t get to work!!

    How about the Fuel Pressure Regulator?

    Have you looked into the circuit that powers the fuel pump? You should check out everything that is in there: relay, speed controller, resistor, oil pressure switch, etc. I'm not saying that you have all of these things, but whatever is in there should be looked at. Remember that the circuit that powers the pump for priming (the buzz before you start the engine) is seperate from the circuit that powers the pump while the engine is running.

    "All right...who keeps squirting this oil in my driveway?"
     
  3. HarryH3

    HarryH3 1 ton status Author

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    Re: Can\'t get to work!!

    First, stop throwing random parts at it. That could end up costing more than taking it to a shop in the first place.

    The IAC (Idle Air Control) motor has a 4-wire connector going to it. It's a tiny stepper motor and moves a small pintle in and out of an air bleed hole in the throttle body. Letting more air in raises the idle speed, letting less in lowers it. If it were bad you would have idle quality problems, not driveability problems.

    Don't be fooled just because there's a computer running things. Infernal ;-) combustion engines still need air, fuel and spark in order to run. Basic troubleshooting of those items first can save you a lot of money in sensors that don't need replaced. Check the fuel pressure and make sure you have good spark. It could be something as simple as a bad ignition module or coil.

    My wife's '94 Suburban decided it didn't want to start, just a few weeks after we bought it. Ran fine on the way to the store, wouldn't start 10 minutes later. I had her crank it over while I was under the hood and could hear the spark cracking against the engine somewhere. A carbon track had formed on the coil tower so that the spark to the distibutor was following the carbon out from under the boot and jumping to the air cleaner housing. Scraped the carbon off with my pocketknife and the truck ran fine. Makes me wonder if that malady was why the previous owner got rid if it!

    So don't just keep buying expensive sensors and such in the hope that it "might" fix the problem. Get some good shop manuals and follow the troubleshooting flow charts. You'll learn a lot about what makes your rig tick and save a TON of money in the long run.

    <font color=black>HarryH3 - '75 K5</font color=black>
    http://ThunderTruck.ColoradoK5.com
     
  4. 89K5

    89K5 1/2 ton status

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    Re: Can\'t get to work!!

    The idle does the same as when I try full throttle - normal to low/almost stall rpms. I think before I take it to a shop I'll clean the idle air control valve, then check the TBI gasket, and fuel pressure regulator. After that it'll be in the shop unless the weather gets warmer, which its supposed to in the next couple of days. I have the Haynes manuals but there still in storage from a recent move.
     
  5. Thunder

    Thunder 3/4 ton status

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    Re: Can\'t get to work!!

    You need to find out where the problem is. To do that you need a code scanner. Your computer will tell you the area where to look. You can buy a cheap one for around 20.00 that uses the check engine light to tell tell you the basics. Or for around 160.00 you can get an auto x-ray scanner with a LCD readout screen that givs a lot more info. I have one and it works very well for diagnosing driveability problems. Also Get a manual. Using a manual and scanner is a lot cheaper than blindly replacing parts. Get a scanner, and post the code you get. I'm sure then we can help you a little more more. There are a lot of knowlageable people on this board who can help if we know the codes.
     
  6. realsquash

    realsquash 1/2 ton status

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    Re: Can\'t get to work!!

    If you just start it up in the morning and let it idle for about 15 minutes in the driveway, does it run fine?

    It doesn't sound like the IAC because the IAC completely leaves the picture except at 0% throttle. It could be the fuel pump, but I would check the pressure on that before spending $$$ on it.

    Be more specific about how it's running! Does it do it on a cruise? Does it do it constantly? Does it buck? Does it hunt at idle? Does it surge under full throttle?

    Squash
    http://www.trailrunners4x4.org/users/realsquash
     
  7. 89K5

    89K5 1/2 ton status

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    Re: Can\'t get to work!!

    I have the code scanner. I've been getting the EGR code for a while. Replaced it last spring. When I had it to the shop, in warm weather, they said it was running rich, replaced a vacuum hose and that was it. It ran fine for them because it got warm out.
    It ran bad from idle through getting warm and when warm. But it hasn't always run bad when warm. if I floor it it feels like its getting gas, but not air. I may be wrong but thats how it FEELS. When floored or half way itfeels like it gets gas a just won't go, then it will take off. Its seems like the same rhythm when idling and when giving it throttle, goes fine, dies, goes fine, dies...
    I just pulled the Idle air control valve. Its dirty, but the spring has no tension and I can't move the plunger. Should I be able to push the plunger in? I'm going to put it back in and take it for a ride, then repost.
     
  8. 89K5

    89K5 1/2 ton status

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    Re: Can\'t get to work!!

    OK looking at the injectors, the left always has gas come out, the right only in spurts!!!! Is it the injector? Or something before the injector? If its the injector, is it an easy fix? How?
     
  9. Thunder

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    Re: Can\'t get to work!!

    You should be getting a fairly circular pattern of spray out of the injectors. If gas is comming out in spurts or a irregular pattern the injectors or fuel meeter/regulator may be bad. The cone shaped assembly that the injectors fit in is the fuel meeter/regulator assembly. I think it has to be replaiced as a unit. The Injectors should be replaiced in pairs.
    The idle air controll valve is controlled by a small internal motor. I dont think you can move it in and out with your finger.

    To get the injectors out squeese the tabs togeather to pull off the electrical connector. Then carefully pry the injector out of the fuel meeter body. it comes out as a unit. hope this helps
     
  10. 89K5

    89K5 1/2 ton status

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    Re: Can\'t get to work!!

    Thanks Thumper. I'm going to seeif they have them at the local dealership.
     
  11. 89K5

    89K5 1/2 ton status

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    Re: Can\'t get to work!!

    I switched the connection on the injectors and the right side continued to spurt intermitently. Injector was bad. Replaced it, problem gone. I only replaced one. Its a fairly simple change, so if the other one goes bad I'll just take care of it then.
     
  12. HarryH3

    HarryH3 1 ton status Author

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    Re: Can\'t get to work!!

    Aren't you glad you didn't replace the $60 IAC motor? [​IMG]

    <font color=black>HarryH3 - '75 K5</font color=black>
    http://ThunderTruck.ColoradoK5.com
     
  13. 89K5

    89K5 1/2 ton status

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    Re: Can\'t get to work!!

    Ya, I'm glad I didn't spend the $60. But I'm learning! I'm sure I saved some bucks figuring it out myself rather than taking it to a shop. They would've taken many hours to figure it out at $65/hr.
     
  14. Thunder

    Thunder 3/4 ton status

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    Re: Can\'t get to work!!

    I,m glad your problem's fixed. I hope thats the end of them. I also have a 89K5 and do all my own work and enjoy it a lot. Its also been a learning experence for me as its the first truck i'v owned with TBI.
     

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