83 350 runs horrid starting when cold

[CoMtGuy]

83 K2500, 350CID, Q-Jet 4bbl, manual transmission:

When warm or slight cool weather the truck starts immediately and runs smooth.

When cold it starts okbut runs horrid, shuddering and rough until it has run a few minutes and you have to work the throttle to keep it running. I've checked the vacuums lines and hoses, replaced anything sketchy.

Once warmed up it is smooth as silk, but a beast cold and sounds like it is missing or something, then after a few minutes it will smooth out. The colder it gets outside the worse the problem.

help, please?

 

[Georgeb]

Make sure your choke linkage is working smoothly and that it is dropping fully closed before starting the truck. Make adjustments as required.

 

[rich weyand]

Is your choke plate closing when it is cold out?

Do you, before trying to start it, push the throttle pedal all the way to the floor once, to release the choke from the cam detent so it can reset to its cold position?

 

[CoMtGuy]

Is your choke plate closing when it is cold out?

Do you, before trying to start it, push the throttle pedal all the way to the floor once, to release the choke from the cam detent so it can reset to its cold position?

Yes, smooth stroke clear to the floor, ease back off to about 20% and fire it. When it's cold outside, should I pull the breather and it should be fully closed before even attempting to start, or do I need check it after I fire it up?

 

[Georgeb]

Yes, should be fully closed before starting it. Make sure it is before atarting it. Assumeing its a q-jet make sure once it starts that its not opening too far but that the vacuum operated pull off is opening it slightly like about a 1/4" gap.....

 

[CoMtGuy]

Rich... I think I understand, let's see if I'm right. Pull the cleaner, depress the pedal like normal, don't fire it up, go check to see if the choke is fully closed, right?

 

[Georgeb]

You can open the throttle from under the hood by actuating the carb by hand and watch whats happening.

 

[CoMtGuy]

You can open the throttle from under the hood by actuating the carb by hand and watch whats happening.

Geez, that's too obvious, thanks for the sanity check. I'll do this tomorrow morning, it should be plenty chilly, and I'll come back and let you guys know the results. Thanks for the advice!

 

[Georgeb]

I take it yours is the round black housing held by three screws. If it doesnt close all the way and the linkage is free adjust it by loosening the screws and turning it until the choke just closes you can give it a little pre-load but not much. Perhaps one hatch mark on the housing after fully closed. Just try to remember what you did so you can backtrack if needed.

 

[rich weyand]

Also, my truck doesn't like ANY throttle to start, ever. I push once to the floor, and release, and hit the key, and that's it.

 

[rich weyand]

I take it yours is the round black housing held by three screws. If it doesnt close all the way and the linkage is free adjust it by loosening the screws and turning it until the choke just closes you can give it a little pre-load but not much. Perhaps one hatch mark on the housing after fully closed. Just try to remember what you did so you can backtrack if needed.

Yeah, the other way to adjust it is get the truck warmed up, shut it off. Then adjust the choke housing until the choke plate just starts to move closed, and back it up one notch.

 

[CoMtGuy]

I wish it had screws, it has rivets! I can't see any way to adjust the choke plastic housing and the manual says to bend the rod.

I've been thinking of drilling them out and finding some self-tapping screws. Any thoughts?

 

[Georgeb]

I would look tomsee what its doing first. Bending the rod may work if done as prescribed in the manual. Otherwise self tapping screws or tapping the holes is an option.

 

[CoMtGuy]

Thanks guys, I'll let you know one way or the other if it required adjust and fixed the problem, or if it seems to be right.

 

[Quadrajet Power]

You can drill them out and use self tappers to adjust it.

Here is my adjustment sheet that has a little section on chokes. It might help.
https://www.dropbox.com/s/ht38b7uknu0yuwc/quadrajet power llc adjustments.pdf?dl=0