What is the factory setting for the fuel mixture screw on a toyota 1.8 litre 2Y engine

There should only be 1 screw located at the base of the carb facing outward.

The method I use requires a tachometer. If you don't have a tachometer then you can use the "by ear" method, though it's not as accurate.

With the engine off, start by turning the screw all the way in, then back it out 1 and 1/2 turns. This usually give you a baseline to start with.

Start the engine and get it up to operating temperature, make sure the choke is fully open, and have the air cleaner and all vacuum lines installed.

Using the tachometer (or ear) turn the screw (usually out) until the RPMs increase. If they don't increase by turning the screw out, then try turning it in.

Eventually the RPMs will stop climbing while turning the screw (as said earlier, usually out).

THEN turn the screw the opposite direction (usually in) until the RPMs JUST start to drop off. That should be real close to the optimum setting.

This setting is ONLY for the base idle air/fuel mixture and is NOT for anything else.

Hope this helps.

Unless your engine has a carburetor, you can't adjust your fuel mixture. That is done by your cars computer. It analyzes your exhaust emissions and adjusts your fuel/air ratio.
Your oxygen sensor(s) may need to be replaced, or there may be a computer glitch causing the problem.

Remove No. 1 spark plug turn engine over till you feel compression on No.1, line up marks on crank pully and timing gear cover , fit distributer making sure rotor points to No. 1 on dist.cap rotate distributer till contacts just start to open .start engine and reset with timing light.

for the Asin 2bbl try from closed position (close gently) open approx.
1-1/2 to 1-3/4 as a starting point. Then with a tachometer hooked up slowly and carefully adjust in either direction to obtain highest RPM.

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Before you could adjust the mixture, make sure that the spark plug gaps, ignition timing and valve clearance are all OK.
- Start the engine and bring it at operating temperature.
- Adjust the throttle stop screw to bring it at the stable rpm.
- Turn in the idle mixture screw while observing the engine speed till the engine starts to stall. At this point turn out the idle mixture screw and keep on opening slowly till the engine acquire the most stable rpm. Finally adjust the throttle stop screw to obtain the desired idle speed.

Start with the idle needle screw first, the idle mixture screw. Seat it all the way in, first-don't overtighten and damage it, just seat it lightly, and back out two full turns. Run the engine and set the adjustment by ear to get your best lean idle: start turning the screw in (clockwise) 1/8 or 1/4 turn at a time till engine stumbles, dies, or runs rough. Keep the engine running, and turn screw out (counterclockwise) a little at a time till you hear the idle dropping. Now between those two settings is your best lean idle. Turn the screw in, a little at a time and wait for engine to respond, tiill you get the highest idle speed. Now set the other idle screw, curb idle, to the idle setting for your truck, probably about 700 rpm. You can move back and forth between the screws to get the best steady idle. Just don't over do it on the idle mixture screw.
Good luck.

High HC counts are due to a rich mixture, too much fuel. How does the truck run normally? To adjust the fuel mixture at the carburetor, make sure the truck is at operating temperature. Turn the idle mixture screw clockwise until the engine starts to lag then turn the screw back just until it runs smooth. Also make sure you have fresh oil as this could cause high HC's as well since fuel gets into the oil and make sure your PCV valve is operating correctly. If you can't get it adjusted correctly, you may have to pay a shop to hook it up to the emissions machine to get the mixture correct, unfortunately.
Hope this helps. Good luck!

If the vehicle is still running original systems then you would need to take it to someone with 1 of the hand programmers to readjust the fuel system settings. If this vehicle has been converted over to or originally was a carborated There are typically 2-4 mixture screws depending on the unit. They will be infront of and behind the carborator. To adjust a carborated you will typically take a flat head screw driver and turn all the way to the right till they are only "finger tight" Once there, note a starting point and from there VIA each screws individual starting point. Turn them all 1 1/2 turns, this will place the carborator at the factory starting position. From there you can then start the vehicle and while it's idleing you can begin to adjust all mixture screws by turning 1/2 a turn till the vehicle looks, sounds, and smells like it is running correctly.

Another method I have seen is using a vaccume pump to register preasure, there are some video's out there to do this method and it can help you fine tune it a little more then one can just by ear. I hope this has helped you or atleast set you in a direction to getting the issue solved.

They quit puting fuel mixture screws in cars back in the 80s. besides yours should be fuel injected. computers do that now.

Yes, Colorado is much higher in altitude. Do to higher altitude the barometric pressure is less than sea level by a long shot. Lower barometric pressure mean that less air is entering your engine. Which in turns mean that your engine is now running richer than it was at a a lower altitude. So I recommend checking you engine timing, and adjusting your carbs air/fuel mixture. yes this means that you may need to rejet. but first there is a screw on your 22r's carb that you must adjust to lean the air mixture just right. I have had a stock 22r carbortor before and never had to rejet it. i probibly should have but it ran fine at sea level and all the way to about 10000 ft. after 10000 feet i had to lean the fuel mixture to even alow the engine to run. This screw that you must turn is hidden due to toyota not wanting you to tamper with it and burn your engine to the ground by running your engine to lean. it has a metal plug on the passenger side of the carb about the size of a pencil eraser. you must drill that out and then you can adjust the air fuel mixture. Clock wise is to lean the air fuel. and Counter clock wise is to richen the air fuel mixture.A good rule of thumb is to turn the air/fuel screw all the way clock wise and then back out about 2 and 1/2 turns. That is the factory adjustment. you may only need 2 turns out. Best of luck i hope you get it running perfect. Try this adjustment first then if it still runs rich then think about rejetting.

Here is a picture of what i am talking about.

#1 is the air/fuel mixture, #2 and #3 are cold and warm idle screws.
#4 is a A/c idle adjustment.