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350 will not idle

Discussion in 'The Garage' started by samiam, Jan 1, 2005.

  1. samiam

    samiam Registered Member

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    '73 K5 350 with TH350. Recently started to not idle while in gear. Have changed all vacume lines, adjusted the timing on 8 to 20 degrees, adjusted the carborator, changed the fuel pump and filters, changed the EGR valve, adjusted the idle speed to no avail. Am out of ideas. If you have any suggested, please post them. I am going crazy.
     
  2. R72K5

    R72K5 Banned

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    20 ??

    only need 4 or 6 at the most

    is power brake booster not holding vacuum ?

    carb throttle shaft bushings worn ?

    vacum advance connected to ported source(port above throttle shaft in base of carb) ?

    vacuum line fell off the tranny modulator valve ?

    oh and dont forget make sure carb mounting bolts are tight
     
    Last edited: Jan 1, 2005
  3. samiam

    samiam Registered Member

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    350 wont idle

    Vacum booster is new maybe a year old, when the vacum line is pulled off it sounds like it is working. How do you test to be sure? I tried spraying WD 40 on any possible leak to see if the idle increased. No results.
     
  4. diesel4me

    diesel4me 1 ton status Premium Member

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    idle stop solenoid??

    Does your carb have an idle stop solenoid??--if it does,and its not working due to blown fuse,bad wire,or bad solenoid,the engine wont idle,as this solenoid is what opens the throttle butterflies enough and sets the idle speed.and closes them when you shut the engine off,to prevent "dieseling"(running on after shutting the key off).
    Other than that ,vacuum leaks are the next most common cause,it would have to be a big one to make it stall,like the PCV valve or hose,Power brake hose and/or booster,carb base gasket,etc--In rare cases the intake can crack between the heat riser or EGR passages and the intake passage under the carb,(sends exhaust into the motor via the intake)or underneath in the "valley" where the lifters are,causing aa vacuum leak..If you have an EGR valve,it will kill the motor at idle if it sticks open...:crazy:
     
  5. R72K5

    R72K5 Banned

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    yeh booster is fine if holds vacuum after engine is shut off

    make sure carb is bolted tight, check hoses and adjust timing with gun and check manifold vacuum with guage make sure it reads 18-22 and steady needle
     
  6. Quaddawg

    Quaddawg 1/2 ton status

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    You didn't say what carb you had, I am assuming you have the Qjet. It's funny, but I was pulling folks out of the snow last week, and my 78 K10 (350/350) started doing the same thing. I really only got this truck a couple of weeks ago, and am still getting the bugs out of it.. Truck ran fine, but didn't want to idle. vacuum lines fines.. etc... I have an Edlebrock carb, but it ended up being some debris in one of the idle mixture circuits.. I took out both mixture screws and cleaned them up, and sprayed some cleaner and such, and it has been fine since.


    One thing though, this motor doesn't seem to want to pull enough vacuum... I have advanced the timing, and messed with just about everything and it only pulls 15-16 at 1000 RPM, It pulls strong, and I have only tried my vacuum gauge, and I am not sure it is accurate, but what else will give consistanly low vacuum readings? I do have some blow by, I guess it could just be in need of a new Edlebrock crate mill... :D
     

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