So my choke seems to be the issue..

[ky_kid]

When the engine is warmed completely the choke will not open all the way. I can open it manually, but any throttle sends it back to partially closed again. It is killing my power and economy. How do I keep it from closing? And is this causing the black smoke and soot from the exhaust?

[ky_kid]

Could it be a problem with the pull-out?

[notyo_cheez]

My guess, choke thermostat has failed. If you have a Chilton's manual there is a procedure to check/adjust it, can't remember...

[C-10 simplex]

The pull off wouldn't be the problem because it's only there for the first 30 secs or so after starting---it's job is just to crack the choke plate open a bit in order to prevent over-richness. But it doesn't have anything to do with normal choke function in terms of "open" and "closed."


2) yes, it could cause black smoke. Although idle-mix screws out of adjustment could also.

The choke needs to be adjusted or i agree with cheez----the thermostat is bad and needs to be replaced.


3) i don't mean to talk down, but chilton's sucks. There are pretty good online sources to find out about choke adjustment. Free too.

[tucsonjwt]

I am sure everyone here is tired of seeing me post this, but get a $12 manual choke conversion kit and be done with it - simple and sure fix. I never had an automatic choke, hot air or electric, work properly. Let me know if you need some specific pics/tips on easy manual choke conversion.

[ky_kid]

Ok here's what it's doing. When the engine is warm, everytime it gets throttle it kicks the choke plate closed a bit. I can click the cam lever (I think) and it stays open. But again any throttle "trips" it back closed. I am considering the manual swap but the carb and everything is mostly brand new. Yesterday I thought I fixed it but it started again today. Kills my power and mpg...
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[tucsonjwt]

If the manual conversion does not solve your problem (which I doubt) you can always go back to your stock setup and continue fiddling with it.

[C-10 simplex]

This points to either the choke coil (the thing inside the black circular thing) is either bad---needs to be replaced. Or the choke is mis-adjusted.


How cold is it in Montana now? (probably a dumb question.......)


If the engine is cold and you can pump the throttle all the way with your hand----in other words you are standing outside and can look at the carb, does the choke blade snap shut like an alligator chomping down on a bird or fish or something. Or does it sort of not close as quickly/tightly?


We/i really need to get some pictures up.

[beamn7]

Sounds like there is too much tension on the choke coil..

With the engine cold, open the throttle once and let it return. The choke plate should now be closed. On the choke coil (black round thing with one wire going into it on the pass side of the carb) there should be 3 screws clamping it to the housing (if they are rivets instead of screws, drill them out and install screws, usually comes with a carb overhaul kit), loosen the screws and turn the black section of the assembly clockwise (if I recall....) until the choke plate opens slightly. Then turn it counter-clockwise just until the plate closes snug and then turn it just a hair more (about 2 degrees) and tighten down the screws. Fire her up, let it run on high idle for about 30 sec and give the throttle a kick, should drop to intermediate idle for approx 1 min, another kick and you should be on base idle and the choke plate should be wide open.

[ky_kid]

Thanks guys I will check the tension on the coil. That sounds like it could be the issue so I'll check it now since it's been sitting.

BTW, last light was in the 20's and we got at least 4-5 inches by morning...

[ky_kid]

That helped... Could I just need a cleaning, like it is gummed up or something. That too easy to work?
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[beamn7]

May want to make sure the linkage is not binding / gummed, etc. Choke plate should move freely in the air horn of the carburetor. Lube the linkage (both sides of carb) with some WD-40 or similiar....

[cjlinkster]

My truck is sort of doing the same thing. It seems like the choke doesn't ever pull off all the way.

I think that I have it figured out. On my 1984 there is a secondary pull off on the back of the carb. This pull off is controlled by vacuum coming from the air cleaner temp vacuum switch. On my truck, I think that the air cleaner ported vacuum switch has gone bad.

Something to check...

Does your truck have the factory air cleaner? Does it have the heat pipe in place for the thermac to operate correctly? If the heat pipe is missing, then the temp vacuum switch in the air cleaner housing will not get hot enough to work correctly, so the secondary pull off will not be able to do its job.

[ky_kid]

I adjusted the tension and shot it with some gumout and it is working great.

Clink, you bring up a point about the air cleaner that got me wondering. It is not a factory air cleaner, but the engine is a gm crate with a new quadra-jet. How can I test the secondaries? Seems like it doesn't gain much by giving it full throttle uphill or under load. But maybe I'm just wanting more power...
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