Throttle/choke jam-up

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AlexArrow
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My tercel:: 1986 Toyota Tercel SR5 Wagon 4WD
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Throttle/choke jam-up

Post by AlexArrow »

First of all, when I got my '86 SR5, it had no carb, so I used one off an '87 base model.
The problem I'm having is difficulty with idling when cold. Checking the carb over, I notice the choke valve was stuck open. Upon investigating, I found a pin jamming up on the choke cam(pictured). It can get stuck on either side of the cam and prevent the choke from moving. Moving the throttle open causes it to jam the choke open.
Is there an incompatibility problem, incorrectly installed, damaged or other?

20211111_2.jpg
Red=throttle, orange=choke linkage, and yellow=sides of cam.

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dlb
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Re: Throttle/choke jam-up

Post by dlb »

That's odd. The only real difference between various carbs is the emissions stuff. AFAIK the throttle linkage never changed.

Do you have any clearer pictures? Is the thing circled in red the pin that is jamming it up? I wonder if something on the cam is slightly off alignment, or if there is a buildup of corrosion there.
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AlexArrow
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Re: Throttle/choke jam-up

Post by AlexArrow »

Sorry, tight space for taking a photo.
The throttle's red pin jams up at the yellow sides of that choke cam when it or the throttle are moved enough.
Move the choke far, it gets stuck closed. Move the throttle far, the choke gets stuck open.
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NWMO
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Re: Throttle/choke jam-up

Post by NWMO »

I believe this cam should keep the choke valve closed for start up and cold idle. Upon warming up, the choke valve should open. There is an associated choke spring that can be adjusted as well OR a spring is missing, throwing off proper operation.
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AlexArrow
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Re: Throttle/choke jam-up

Post by AlexArrow »

Well, I re-assembled that part and adjusted the choke and it is all good now. Also helped to plug the vacuum line going to the air cleaner while it is off.
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Petros
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Re: Throttle/choke jam-up

Post by Petros »

you should not try to dianose a problem with any loose vac line not blocked off.

something occurred to me rereading your post, you said the carb is from an 87 "base model", do you mean a Tercel4wd wagon? or a base model tercel sedan. the sedan completely changed the engine configuration in 1987, it is not the same as the '83-88 wagon, nor even the '83-86 sedan and hatch back. Although the carb is similar, I have seen this mistake done before, it can be made to run, but you will never get the vac lines sorted out because they are very different.

You can use any carb from 83-86 from any model of tercel, 4x4 or front WD, there are slight differences, but they should be all cross compatible. and you can use any carb from the '87-88 wagon only.

Good luck.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
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dlb
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Re: Throttle/choke jam-up

Post by dlb »

Petros makes an excellent point. I hadn't thought of that. Good catch, Peter.
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AlexArrow
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Re: Throttle/choke jam-up

Post by AlexArrow »

I meant that they are both 4wd wagons, but the parts car was an 87 'base' model and my car is an 86 SR5.
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Petros
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Re: Throttle/choke jam-up

Post by Petros »

AlexArrow wrote: Sat Dec 04, 2021 2:49 pm I meant that they are both 4wd wagons, but the parts car was an 87 'base' model and my car is an 86 SR5.
okay, usually people describe them as DX or SR5. no matter, those carbs should be almost identical and interchangeable. Many people get the wrong parts when they own a 1987 or 88 wagon and order it for an '87 "tercel". they are not the same, during a strange staggering of model years.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
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