First carb rebuild...hard earned success

FJ Noob

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Whew. Lots of info in this but it's basically like the green stuff in a bike tire...it gels up and blocks small passages to stop leaks. Problem is the whole radiator and heater core are small passages, so it severely limits the flow. It gets everywhere and you can't get it out. Basically ruins your cooling system. If you want to keep it in your truck in case your stranded and alone and have no other options, go for it but plan on replacing your radiator and heater core(s) when you get home, and know it will still probably be lining all thnme water jackets in your engine. Awful band-aid of a fix that has no place for a car of value.

EDIT: if you'd like to see what it does to a core tube, look it up on YouTube. You'll find a number of frustrated mechanics who cut open the junk radiators so people can see

Thanks for the explanation. Sounds like awesome stuff :confused: ....ugghh why would anyone keep selling it and not advertise the downsides?!? Never would have looked it up because it's so prevalent in all the stores.
 

FJ Noob

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Ok MUD community, got a question....can anyone identify this part? I started my carb disassembly and this was just floating around in the bowl. It’s a big rubber o-ring? Haven’t seen it in Pin Head’s video series and don’t recognize it in any of the parts schematics either.

952B500F-8B76-421D-A164-BF16D762B6EB.jpeg
 

FJ Noob

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To add to that, they are Part Number 21659-38110 in this diagram (on top of venturies near upper left):
Thanks! With both replies I get the whole picture now. I was focusing on the wrong part because the second gasket fell out of somewhere when I separated the air horn and body. Based on what I’ve been finding, I’m surprised the truck was running as well as it was until now.
 

FJ Noob

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Carb is rebuilt and put back in the truck. I was hoping to jump right into going through the "lean drop" adjustment procedures per the FSM. She fires right up and sounds stronger, BUT dies out right away when I push the choke in. The way I read the FSM, I need to get it running with no choke before I can make adjustments. Besides cleaning, I didn't change any adjustments expect for pulling the idle mixture screw out to clean. I seated it lightly and backed off 2 turns per the FSM.

Any ideas what is the most likely culprit or advice on how to start narrowing down the potential issues?

Pretty sure the linkages are correct
IMG_0441.jpeg


Does look nicer in there...too bad she doesn't want to idle.
IMG_0450.jpeg
IMG_0452.jpeg
 

FJ Noob

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The only other thing I deviated from was the gasket. I used the style on the right as it matched the picture in the FSM. The style on the left is what was in there when I opened it up.
04B60307-443A-4724-A3A1-F08F349146F2.jpeg
 

NeverGiveUpYota

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What is going on with your slow cut valve? I see the two screws that hold it but it appears to have hole where the valve was... Open the IM more than 2. Jim might say more like 3, depending on your location and elevation, some go as far as 4-5... mark the head of the screw half with a visible sharpie color to keep track of counting turns.
 

FJ Noob

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What is going on with your slow cut valve? I see the two screws that hold it but it appears to have hole where the valve was... Open the IM more than 2. Jim might say more like 3... mark the head of the screw half with a visible sharpie color to keep track of counting turns.
No hole in the SCV, you're seeing where the allen key would go. Removed the plunger, tapped it and JB welded a set screw in.

Tried backing it out another turn or two and it still dies out. Takes a little bit longer, but still dies.
 

NeverGiveUpYota

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Your lucky the book is on my coffee table cuz I’m lazy as heck after work and wasn’t about to get up.
IM screw is where the notation ‘steel plug’ is written. In the middle of the ports on the back of the carb.

DF62E08F-3A5D-4F1E-918D-524E77FBB50E.jpeg


F76FA2FE-E818-4173-BE6F-65119BDDB2B3.jpeg

To adjust the carb WITH the air cleaner housing on you’ll need to make one of these. Don a thick glove, hold this in your right hand to turn the screw (this is where marking the head half w/ colored sharpie helps) and count while you peer around the left side while holding a flashlight in your mouth.

15A62555-A548-4A72-A1F8-5B5481580A32.jpeg
 
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FJ Noob

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No IM (idle mix) is on the back side facing the valve cover. The red is Idle Speed and the yellow is Fast Idle.
Yeah, mixed that up. What you said is what I meant. Progress though....without fabricating a screwdriver, I'm able to get it to idle and keep going around 900-950 rpm. That's with me constantly popping the air cleaner off and guessing.

Guess I'll make a tool. I think I just need to fine tune from here, but I'm not quite sure about the direction to turn the idle mix. I can't here a change in rpm no which way I turn it. I can hear the difference with the idle speed; backing out lowers rpm. Generally speaking, should I be trying to increase or decrease the fuel at the mix screw?

Since I picked the truck up, it always idled fast (~1000rpm). Just figured I'd adjust when I did the carb. I'm hoping it wasn't set at 1000 to compensate for something else. I squirted some carb cleaner around the lines and got no response like there's a leak causing higher rpm.

QUESTION FOR THE COMMUNITY: What activates the fuel cut-off solenoid? I ask because when I was looking earlier, fuel was coming from the venturi during idle. If I understand the circuit correctly, fuel for idle should be pulled from the inner opening of the idle mix screw and not the venturi.
 
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FJ Noob

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Talking out loud here...

I assume the fuel cut off solenoid is getting power and "on" when you turn the key to at least ACC, allowing fuel to pass into the circuit. It stays "on" until you turn the truck off.

If I'm not getting fuel through the idle circuit at idle and it's coming from the primary nozzle instead, there is only so many parts of the idle circuit that could go bad.

The solenoid checks out. The idle jet was cleaned and was clear. Power pump moved freely. Idle mixture adjustment screw passage was clear when cleaner was sprayed through.

Check the throttle valve clearance? With valves closed at idle, there should be vacuum below and "no" vacuum above. If it's allowing "vacuum" to pull from the top side, it would pull from the primary nozzle and possibly not the idle circuit...or at least would nullify any fuel coming past the idle mix screw.

Sound about right or at least a plausible place to start?
 

Pin_Head

 
 
 
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It sounds like you either have a problem with a lack of idle fuel or a manifold vacuum leak. It is hard to distinguish these two causes.
The smog computer and the manifold vacuum sensor ground the idle fuel cut off solenoid, allowing fuel to flow. I think that this is the yellow wire. Disconnect the solenoid, turn the key on and see which wire is hot. Ground the other wire and see if the problem goes away. It could also be due to a plugged idle fuel circuit. This is something that you always check when rebuilding a carb. If the idle circuit checks out, start looking for a manifold leak, including the EGR valve, brake booster and all the other vacuum connections.
 

NeverGiveUpYota

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Carb is rebuilt and put back in the truck. I was hoping to jump right into going through the "lean drop" adjustment procedures per the FSM. She fires right up and sounds stronger, BUT dies out right away when I push the choke in. The way I read the FSM, I need to get it running with no choke before I can make adjustments. Besides cleaning, I didn't change any adjustments expect for pulling the idle mixture screw out to clean. I seated it lightly and backed off 2 turns per the FSM.

Any ideas what is the most likely culprit or advice on how to start narrowing down the potential issues?

Pretty sure the linkages are correctView attachment 2134912

Does look nicer in there...too bad she doesn't want to idle.
View attachment 2134913View attachment 2134916
Another thing I see in this photo is a big gob of grease on that pivoting link. Clean it off. It should be clean metal. You can scour it with a scotchbrite pad but loading it up with grease is setting it up for getting gummed up with debris.
 

Robert Franzke

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QUESTION FOR THE COMMUNITY: What activates the fuel cut-off solenoid?
The smog computer and the manifold vacuum sensor ground the idle fuel cut off solenoid, allowing fuel to flow. I think that this is the yellow wire. Disconnect the solenoid, turn the key on and see which wire is hot. Ground the other wire and see if the problem goes away.

FCS is controlled by the Emissions 'computer'. Believe it or not these 60 series have a PCB board behind the drivers side kick panel. Controls various things, including the activation of the solenoid. Its activated by closing the ground side of the solenoid and only closes during decel or power cut off at the key as I understand it. There is a vacuum switch that sends a signal to the emissions computer based on vacuum to turn if on or off. Used to prevent unburned fuel when decelerating from entering the exhaust system and to prevent the engine dieseling after engine shutoff. Here is info from the FSM which tells in what situations the FCS is opened or closed:

ICS2.jpg


And a great video actually showing the FCS actually functioning while operating the truck:



I ran into an FCS issue on my truck sometime back here. Lots of info on the FCS in that thread.

Always interested me the ways Toyota came up with to handle various things in these trucks.
 

Robert Franzke

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Never run through this procedure myself but seemed to be plausible when I viewed it. Maybe others can chime in as to if this works well or not. Sounds like you are getting her pretty well dialed in now so might not be useful but thought I would add in case it is. Sorry for the distractions here. Carry on.

 

NeverGiveUpYota

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FCS is controlled by the Emissions 'computer'. Believe it or not these 60 series have a PCB board behind the drivers side kick panel. Controls various things, including the activation of the solenoid. Its activated by closing the ground side of the solenoid and only closes during decel or power cut off at the key as I understand it. There is a vacuum switch that sends a signal to the emissions computer based on vacuum to turn if on or off. Used to prevent unburned fuel when decelerating from entering the exhaust system and to prevent the engine dieseling after engine shutoff. Here is info from the FSM which tells in what situations the FCS is opened or closed:

View attachment 2135283

And a great video actually showing the FCS actually functioning while operating the truck:



I ran into an FCS issue on my truck sometime back here. Lots of info on the FCS in that thread.

Always interested me the ways Toyota came up with to handle various things in these trucks.
And if it seems to be the EC is faulty (because as @Pin_Head said grounding it DOES enable the FCS to work) , I began this thread awhile back on reflowing the solder points which may be cracked... Reflowing Solder Points
 
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