I'm such a noob, please have a little patience with me.

Extremely difficult cold start on a '85 22R, even when the weather is warm.

Everything seems to be stock, but the wiring harness has been butchered in a lot of places. So I'm having trouble finding this electric choke thing I keep reading about.

I don't know much of what I'm looking at. My area of experience is motorcycle carbs, not automotive ones. I didn't even know where the choke plate was till I searched here for everything I could find (thanks!)

The part where something electric controls the choke operation baffles me. I don't know what I'm looking at, or what it SHOULD look like. I have a Haynes but the terminology is pretty confusing and the diagrams, even more.

I'd be perfectly happy operating the choke manually, like I do on my motorcycles.

I searched for information here but maybe I've missed something obvious. I just need to find out what's missing, or mis-adjusted, or not hooked up, and get the truck to start without having to keep my foot on the gas and burn up the starter motor.

Is there a step-by-step trouble shooting guide to help me find why the choke plate isn't being actuated?

Many thanks, and glad to be here!

 

Did I post in the wrong section?

 

You posted in the right section. But we need more information about your rig for one. Year model? Ect. The more info you provide the easier it is for us to help.

Also the search feature on here is ok but I use google a lot to find yotatech information faster and better
See if this link helps
https://www.google.com/search?q=plea...tech.com&hl=en

Welcome to the site

 

My year and model is in my sig.

I'll search again, with Google.

 

The Blue Bass link everyone keeps referencing is gone. Has it moved or does it no longer exist?

 

The thread dated November 15 2006. (I think). Has some good info I think. Has info on 3 temp sending units and the keyed wire off the alternator that lets you carb heat up.

 

Well first, the choke is an automatic choke not an electric choke. When it is working correctly, the choke will close automatically, or it will want to close, more on that later. 12 volt power is only used to open the choke. Even though there is a secondary mechanism to remove the entire choke circuit once the engine warms up to operating temperature.

Here is a pic of where the choke is located. It is connected to a singe (red) wire. Ground is provided by the housing.




In this next picture, you can ignore the "choke relay" as the the truck 22R engine does not use one.





Inside the choke housing is the "bi-metal element". It is a spring made of two metals, hence the bi-metal name. This is spring will move with the change in temperature. When it is cold, it will expand and push on the arm to close the choke plate. When it is heated, it will constrict to open the plate.

On a cold engine, to engage the choke plate you must press the gas pedal at least once. What this does is free up any binding there is on the coke plate and the "Fast Idle Cam", see next pic.




Since these two are actuated by springs, when you press on the gas pedal, it allows them to fall into place.

Technically, for a cold engine start, Toyota says to press on the gas pedal three times. What this does is allow the mechanical accelerator pump to squirt fuel into the throat of the carburetor to start the engine.




As the engine is warming up, 12 volt power is fed to the choke heating element inside the choke housing. This in turn heats up the bi-metal spring. This will slowly open the choke plate. However, the normal high idle speed typically does not decrease on its own as the choke plate is being opened. That is because the friction on the Fast Idle Cam is still being held in place. Two things can be done. Either blip the gas peddle to release the friction on the fast Idle Cam, and it will step down to the next "step" of the Fast Idle Cam. Or just wait until the Vacuum Switch Valve (TVSV) routes vacuum to the Choke Opener and that will remove all of the choke and fast idle cam circuits.

 

Perfect!

Thank you!

When I was looking at the carb, I turned the throttle thing (where the cable turns and you can get at it from under the hood), I turned it as far as it would go once, twice. It did not cause any change in either of the two plates I can see in the carb. Not sure which one is the choke plate but replicating "flooring" the pedal from in the engine area didn't cause it to do anything.

My red power wire goes to an oily mess of wiring that isn't mounted correctly, and is kind of hanging under the engine. The red wire goes to a green cylinder with four wires but after that, I'm lost. Now that I know that the red wire is the power wire and that it's grounded through the motor, I can make more sense of the wiring diagram.

My red wire has been re-done at least once. It has an aftermarket blade connector on it.

Thank you again for all this information! it's just what I needed!

 

Wait a minute...If I were to use a jumper wire and connect the red wire to the battery, would that cause the plate to move?

 

When standing in front of the truck (engine), the choke plate is on the left of the two barrel carburetor. The one closest to the fender.

The right plate is part of the secondary barrel. That plate behave as a variable venturi valve. It will never open by hand when operating the throttle mechanism.


It would cause the choke plate to open, only if the plate is in the closed position.

Since your saying the choke plate does not close when opening the throttle valve, either with the gas pedal or rotating the throttle valve by hand, it sounds like you have a malfunctioning choke system.

You might have some of the linkages binding because of the many years of engine compartment built up, or the actual choke housing was opened up and someone did not reinstall the bi-metal spring onto the tab. You can check to see if the choke housing still has the original 3 pop-rivets that hold the black plastic housing to the metal frame.

 

I saw rivets on the black choke housing. So maybe the choke parts are ok, and it's the wiring that's faulty.
But...will I break anything if I jump that red wire straight to the battery? It would allow me to see if the choke is working, and it would allow me to start the truck in cold weather until I can get this done right.

 

I would not recommend wiring the choke wire directly to the battery. Even there is a positive temperature coefficient resistor wired in series with the heating element, there will always be 12 volt power running to it. The way the stock configuration is, only with the alternator is turning, that is when the engine is running, will voltage be applied to the choke heating element.

Since the rivets are still in place, I can only say that the linkages may be preventing the choke plate from closing. The choke plate and the fast idle cam are connected indirectly. Meaning the two can move separately, yet they are connected via spring-loaded linkages.

Try manually opening the throttle by hand all the way by reaching your hand to the backside of the carb. Then, when still opened, close the choke plate by hand, just push down on the plate itself. Release the choke plate, then release the throttle. See if the choke plate remains closed. If so, then you may have either excess friction on the linkages, or weak springs.