Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Engine stalling?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Ditchdigger, Mar 21, 2001.

  1. Ditchdigger

    Ditchdigger Registered Member

    Joined:
    Mar 11, 2001
    Posts:
    96
    Likes Received:
    0
    Location:
    The Great Midwest
    hey guys,
    my carbureted 305 on my 84 is given me trouble
    Its idling normal and I put it in gear and its still idling
    fine, but if I push the pedal too fast it stalls also the same
    thing if I don't put it in gear, If I rev it from idle it'll quit, unless
    I do it slower, and I just rebuilt the carb and adjusted the
    mixture screws to top RPM,
    you guys have any ideas!
    I thought about distributor vacuum advance and wandering if its ok connected to the center, left carb port because I look on my vacuum hose routing sticker and it says theres a vacuum advance delay valve and I don't see anything like that
    its just connected right too the front of carb, is this ok?

    If it ain't Intimidating / It ain't a Chevy!
     
  2. thatK30guy

    thatK30guy 1 ton status Premium Member

    Joined:
    Jan 12, 2001
    Posts:
    32,076
    Likes Received:
    55
    Location:
    .
    Sounds like a choke problem.
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,982
    Likes Received:
    191
    Location:
    Roy WA
    Vacuum advance doesn't (shouldn't) have anything to do with idle/acceleration. It should be connected toa port on the carb that does NOT see vacuum at idle. All you have to do is pull the hose and see if it does when the truck is running. If it does, then you are advancing your timing at idle, and that is not correct.

    Mix screws are not "top RPM" in my opinion, but should be set at the LOWEST setting you can, without the engine "shuddering" form not enough fuel. Typically all the way in, then 3.5-4 turns out on each side. They are tricky.

    Sounds to me more like accelerator pump, although I had a carb that was doing the EXACT same thing. If I floored it in neutral, off the line, whatever, the thing would die. The choke was completely open, and the accelerator pump appeared to be working ok. I just swapped carbs, didn't even dig into this one. I took it apart about 3 times trying to fix the problem, never did. I wouldn't doubt it if it was something on the primary side, like perhaps a sticking power piston that isn't releasing as you give it gas, and the engine loses vacuum..

    You can try, with the truck idling, depressing the accelerator pump, without using the throttle. You should notice some kind of engine RPM change for a second, also you can probably see the stream of fuel. You can check for fuel stream with the engine off BTW.

    Did you replace the check ball for the accelerator pump or at least clean that area out when you rebuilt it? I assume yes....


    Dorian
    My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
     
  4. Ditchdigger

    Ditchdigger Registered Member

    Joined:
    Mar 11, 2001
    Posts:
    96
    Likes Received:
    0
    Location:
    The Great Midwest
    thanks dyeager535, I think I'll look into the advance and make sure I have the right port with no vacuum at idle.

    and screw my mixtures in a little because I'm thinking thats
    the problem

    It looks like the accelpump is working fine and did clean the bearing!

    I hope this does the trick!

    If its not Intimidating / Its not a Chevy!
     
  5. muddin4fun

    muddin4fun 3/4 ton status

    Joined:
    Feb 19, 2001
    Posts:
    5,644
    Likes Received:
    0
    Location:
    N Texas
    I would say that your choke is messing up also

    [​IMG]


    <A target="_blank" HREF=http://muddin4fun.coloradok5.com>http://muddin4fun.coloradok5.com</A>
     
  6. Ditchdigger

    Ditchdigger Registered Member

    Joined:
    Mar 11, 2001
    Posts:
    96
    Likes Received:
    0
    Location:
    The Great Midwest
    Oh yeah, choke is fully open too!

    If it ain't Intimidating / It ain't a Chevy!
     
  7. Goose

    Goose 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    1,127
    Likes Received:
    1
    Location:
    South Central Kansas
    I doubt you have a holley carb, (lucky you), but this sight explains alot about general carb operation and may help you get it adjusted properly
    <A target="_blank" HREF=http://www.holley.com/HiOctn/TechServ/TechInfo/FMCTech.html>http://www.holley.com/HiOctn/TechServ/TechInfo/FMCTech.html</A>
     
  8. Ditchdigger

    Ditchdigger Registered Member

    Joined:
    Mar 11, 2001
    Posts:
    96
    Likes Received:
    0
    Location:
    The Great Midwest
    I've been messing with the mixture screws and wow driving around town like a bat out of hell lots of torque and snappiness but I went on the highway against the wind and she lost some of that power seems to be strugglin getting some speed, then I'll floor it and she'll kickdown and still struggle but will slowly climb in speed
    Just wandering if I should back out or screw in a turn on the mixture

    If it ain't Intimidating / It ain't a Chevy!
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,982
    Likes Received:
    191
    Location:
    Roy WA
    Don't mess with mixture if it idles right. Those screws are called "idle mix screws" for that reason. they are idle mix screws. Something else isn't right if you are losing power. You checked vac. advance? Thats cruising. You could be dealing with mechanical advance problems too, the bushings can wear out and cause the advance weights to bind.

    Dorian
    My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
     

Share This Page