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TBI COLD START *latest drama-EDIT**SOLVED*

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by k20, Nov 27, 2002.

  1. k20

    k20 3/4 ton status

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    Ok, i know theres been a bunch of posts on this lately, and ive tried reading em and doing em. Anyway, I have an 87 K20 with an 89 TBI engine in it. WHen it used to be warm (above 60) the truck started fine. Now thats its dropped to 50 in the afternoons and 30 in the morning, in the morning it wont start. It kicks over strong, but it wont catch. Sometimes itll catch but not fire. It'll do that till it sounds like the batt is gettin to its end, or i hit it w/ a drop of starter fluid. Then in the afternoons after its sat all day, it takes awhile to start, but i dont hafta use up the battery of the fluid. Ive cleaned the IAC, no difference, i checked my heat riser tube and mechanism, no difference. Then last night with the truck off, i messed with the EGR valve. I pushed up on it like people say to do to test it. Well it didnt move at first, but then it moved easier. SO i started it up and it idled im guessin 4-500 RPM's higher (i have no tach). SO i took it around the block, and it seemed to run better, used to be when i would put my foot on the floor at say 40 it would kick down to 1st gear and not go anywhere. SO i did that and it kicked down to 2nd, and actually moved along at a good clip. So today i go out there to restart it, and its back to its old self. What now? As far as performace, ive got a low restriction exhaust and air cleaner, headers, and a chip. Nothing else that could change it. Any ideas? Sorry for it being so long.


    EDIT: Well, today i go outside to start it, its wont start at all, now it'll run on starter fluid, but only till its gone. The fuel pumps run, one in each tank, ive tried both tanks. Ive replaced the fuel filter. Ive changed the rotor, and the IAC. The injectors are gettin pulses according to the NOID(sp?) light. But they are not spraying fuel. SOOO what now? Im praying its not computer probs, but its looking like either that, or a new throttle body...... if it comes to throttle body, the holley one that sprays more is cheaper, and its the whole thing, or parts of the throttle body from GM come to like 75 more and arent even everything. IF i do need a new body, what about the holley? any experiece?
     
  2. k20

    k20 3/4 ton status

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    Re: TBI COLD START

    I 4got to say, that after she starts running, for the first 5 mins of idle, you hafta sit in it, to make sure it dont choke down, constantly playing w/ the throttle, and then it will idle fine, then you get in, put it in gear, and the 1st half mile or so, you hafta do the same thing, it sounds like it wants to die, but it hardly ever does that in the afternoons.
     
  3. YtseJam

    YtseJam 1/2 ton status

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    Re: TBI COLD START

    Start with the basics. Check all of your ignition components, e.g. Cap & Rotor, plugs, wires. Check your fuel pressure. Fuel filter ok? From there have someone crank the engine and listen in the fuel tank to see if you hear the fuel pump running. If not there is a test connector @ the fuel pump relay. You can jump B+ to the the connector and energize the fuel pump. This will indicate a possible faulty fuel peump relay. Start there and see if any of this corrects the problem.
     
  4. k20

    k20 3/4 ton status

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    Re: TBI COLD START

    when i switch the ignition on, i hear the fuel pump run, so its not that.
     
  5. TopOff

    TopOff 1/2 ton status

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    Re: TBI COLD START

    How long have you had the Hypertech installed?

    Do you have the original chip?

    (See where this is going?)

    I have heard the Hypertech can be too rich for the engine when it's cold out and the engine is in open loop (cold).

    Good luck.
     
  6. k20

    k20 3/4 ton status

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    Re: TBI COLD START

    I got a jet chip, but yeh i see where your going with it, i might put the original chip back in tomorow (dependingon what time every1 leaves) or friday andsee what it does...it does sound like too much fuel is getting to it cold, but what would cause it to just not fricking start? I mean its got new plugs (less than 1k on them) fairly new looking wires (ones i bought it with).
     
  7. k20

    k20 3/4 ton status

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    Re: TBI COLD START *latest drama*

    See the first post for edit
     
  8. RockyRider13

    RockyRider13 1/2 ton status

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    Re: TBI COLD START *latest drama*

    I had a similar driveability problem. Ended up being the ignition and coil. Get a book, hook up a multimeter and troubleshoot. Good luck.
     
  9. Thunder

    Thunder 3/4 ton status

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    Re: TBI COLD START *latest drama-EDIT*

    Have you checked for trouble codes ????? It really helps to diagnose the problem if you can post any trouble codes.
    It helps a lot to ask the computer what is wrong.
    And just because you hear the fuel pump running doesn't mean it is good. they can sound just fine and still not be punping enough gas.
    A bad distributor module, coil or pickup module can also cause the computer to shut down the fuel. It wont give fuel if the computer is being told it is not getting spark.
     
  10. k20

    k20 3/4 ton status

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    Re: TBI COLD START *latest drama-EDIT*

    It doesnt have any codes, and it would be highly unlikely for both pumps to go at exactly the same time wouldnt it? And the coil can cause it not to get fuel?
     
  11. YtseJam

    YtseJam 1/2 ton status

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    Re: TBI COLD START *latest drama-EDIT*

    OK, So while the condition is occuring, check for injector pulse at the throttle body using a noid light or a test light. The light should blink while cranking. If not I will explain how to test further. If ok, check for spark while cranking. If no spark occuring during cranking this could indicate several problems. You have varified that the cap and rotor are ok right? The carbon button in the center of the cap is still there too? OK. You can measure the resistance of the pick up coil in the distributor. It should be between 500-1500 ohms. 800 Ohms is usually normal. Test between the 2 wires that connect to the ignition module. Usually pick up coils act up when the vehicle is hot. If it is out of range replace it.
     
  12. k20

    k20 3/4 ton status

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    Re: TBI COLD START *latest drama-EDIT*

    Ok, well today was more money wasted.... I really ahve no testing equipment here, but here goes the latest parts changed. Coil changed, ignition module changed, and cap is verified as ok. The injectors are firing according to the noid light, both of them are. Today, you can get teh truck runnin on starter fluid, and it will idle. However you can let it run for 3 or 4 mins, tap the gas and it dies. Like it is only gettin enough gas to idle, but the second you crack open the throttle only more air goes in, no extra fuel, and it kills it. What now?
     
  13. pr1aw

    pr1aw 1/2 ton status

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    Re: TBI COLD START *latest drama-EDIT*

    Rebuild the fuel pressure regulator inside the TBI, costs about $26 at Auto Zone.
     
  14. k20

    k20 3/4 ton status

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    Re: TBI COLD START *latest drama-EDIT*

    Would a TPS or a engine temperature sensor (one in top of the manifold) be the cause of this?
     
  15. k20

    k20 3/4 ton status

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    SOLVED YAHOOOOOOOOOOO! Ended up being the engine temperature sensor in the intake manifold. It was telling the computer it was 201deg's when it was 50. Thanks for the help.
     
  16. 87sm465np208

    87sm465np208 1/2 ton status

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    its those stupid little things in these engines that make the biggest diffenreces, i swear. /forums/images/graemlins/rotfl.gif

    /forums/images/graemlins/usaflag.gif /forums/images/graemlins/truck.gif
     

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