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1990 K5 TBI won't idle all of a sudden

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by rich, May 25, 2004.

  1. rich

    rich 1/2 ton status

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    1990 K5 TBI won\'t idle all of a sudden

    Hey!

    I have searched, and have found a little bit of info related to this, but no exact answer. Can you help?

    PROBLEM:
    My 1990 K5 Blazer with stock 350 TBI and 193,000 miles will not idle. It will not start unless I keep my foot on the throttle a little. As long as I keep my foot on the gas, it runs fine. If I let off, it will die immediately.

    SITUATION:
    This just happened this morning. My K5 has been running and driving fine - I last drove it to pull my car trailer and a Pinto wagon on Saturday. /forums/images/graemlins/smile.gif I started the K5 this morning and moved my car trailer around, then turned off the K5 so I could unhook the trailer. Decided I would rather leave the K5 running with the A/C on, so I tried to start it back up. No start. Will only start if I keep my foot on the throttle. Had to drive my Suzuki Samurai to work. /forums/images/graemlins/frown.gif

    QUESTION:
    Any ideas? /forums/images/graemlins/smile.gif I am going to pull codes tonite and see if there is anything there. Does this sound like an IAC problem? It IS getting fuel, and again, it runs fine otherwise, just won't idle or start without my foot on the gas.

    Thanks!
    Richard
     
  2. bckinblk

    bckinblk 1/2 ton status

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    Re: 1990 K5 TBI won\'t idle all of a sudden

    Start with the easy stuff first..check the throttle body gasket .Look at all vac lines for leaks.Unbolt Iac and TPS and spray some cleaner in all ports to clean out carbon.If that does'nt work then check the map sensor coolant temp sensor and egr .These are all common problems with the tbi engines..Also look at fuel pressure and fuel filter..Good luck
     
  3. rich

    rich 1/2 ton status

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    Re: 1990 K5 TBI won\'t idle all of a sudden

    Thanks! /forums/images/graemlins/smile.gif I'll start working on it tonite... /forums/images/graemlins/smile.gif
     
  4. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Re: 1990 K5 TBI won\'t idle all of a sudden

    Did this start while driving and coming to a stop? If soe I would start looking at a stuck open EGR. Also check all the Vac lines. The plastice lines on my 88 with only 83k are all failing. I had to replace or repair most of them.
     
  5. rich

    rich 1/2 ton status

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    Re: 1990 K5 TBI won\'t idle all of a sudden

    It happened like this:
    I started it in the morning, and ran it for about 5 minutes to move my car trailer. Started fine, ran fine, no problem. Then I turned it off. Then decided I wanted to leave it running (for the A/C), so I immediately tried to re-start, and that's when the problem began.

    I checked some stuff last night, but it is still not right:
    1) Replaced fuel filter - it needed this bad, you should have seen the nasty black gas in in the inlet side of the old filter. But did not fix problem.
    2) Pulled air cleaner - injectors seem to be firing fine, but I have no other vehicle to compare to.
    3) Noticed that gasket around base of air cleaner was coming apart. Looked like a piece of it might have gotten into the IAC port. Removed IAC - it was NASTY. Sprayed IAC and port with throttle body cleaner and got a bunch of crap out of there. That still did not fix it.
    4) Checked codes, no codes found.
    5) I kept my foot on the gas to keep it running, and I let it warm up all the way. It finally would idle, but lower RPM than usual, and I could make it stumble by turning on/off the A/C and putting it in/out of gear. It would start on its own (without my foot on the gas) about every other try, but even then it did not start right up like it used to.

    NEXT:
    Can't work on it tonite, but I'll be sure to check the EGR valve if I get to work on it Thurs. Will also do some more checking on the IAC. The reason I feel like this may be IAC related is that all it takes is me to BARELY put my foot on the gas to make it start and run fine. Kind of like the IAC isn't doing anything at all.

    Any other ideas?

    Thanks!!!
    Richard
     
  6. wayne

    wayne 3/4 ton status

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    Re: 1990 K5 TBI won\'t idle all of a sudden

    Your TPS might have took a dump. On my 90 what happens is it does not want to start unless you put your foot on the gas. Mine does idle fine though once it was running but the TPS had a dead spot. It will also idle way low sometimes. I have a new TPS and have to replace it but I'm planning to do some other work at the same time.
     
  7. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: 1990 K5 TBI won\'t idle all of a sudden

    Check the CTS too.
     
  8. jekquistk5

    jekquistk5 Weld nekid Premium Member GMOTM Winner

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    Re: 1990 K5 TBI won\'t idle all of a sudden

    Yeah check the EGR valve that was the case on my 90, also check the vacuum lines!
     

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