Need a little carb help. Idle issue.

[CliffClaven]

Alright so it's really obvious after doing a search that this topic has been posted many times before. It seems however that a lot of the threads are problem specific and don't cover the whole picture. I have a FSM for the 2F that talks about WHERE the carb should be set for maximum performance. The FSM also covers the lean drop idle and all of this. Maybe I'm tired of smelling like gas (I have an open header) or maybe I'm just not going about this the proper way.

My carb has 4 screws...Idle mixture, Fast idle speed, idle speed and the AC idle up which I'm not playing with until I get all of this sorted out.

The carb is rebuilt and if I use the choke it will idle just fine around 1200 to 1300 rpm (which is where it should be right?). The FSM wants me to set the fast idle to 1800 rpm, I'm thinking that excessive. My problem is when I push the choke back in the truck will not idle. I've messed with the screw for it and I'm not really sure what I should do...screw it in more or back it out more??? This is where my dilemma lies.

I don't really want to tune this thing with an open header, but I can't get the rig to the exhaust shop a couple blocks down the road unless I can get it to run. With the choke pulled out a hair I could probably get this to the exhaust place, but I'm ready to cruise guys I've been without my rig for a couple months while I had the carb rebuilt and I installed the header and desmogged the rig.

So far this is what I know about tuning the carb;

With the choke pulled out completely adjust the Idle mixture until I get the maximum rpm using the Idle mixture screw. Adjust the Fast Idle screw with the choke pulled to about 1200 rpm. Then adjust the Idle screw with the choke pushed in to around 690 rpm.

Does that sound about right? I just can't seem to get the last step of this down correctly. Can I turn it completely CW or CCW to get the rpms way up there and step it down from there? Which way to turn the screw? There are my problems; I'd like to get this turned (somewhat) tomorrow and in the hands of the exhaust gurus down the road.

Thanks!

 

[Pin_Head]

The idle mix screw doesn't have any effect with the choke on. It only works when the throttle plate is completely closed.
Read the carb info article in tech links that describes how carbs work.
Cruiser Carb Info - Land Cruiser Tech from IH8MUD.com

Also read the vacuum 101 (or your engine sucks) article as it explains manifold vacuum which will help you diagnose the problem.
Vacuum 101 - Land Cruiser Tech from IH8MUD.com

The first thing you need to do is determine if it will idle without pulling fuel out of the main nozzle (which is what the choke makes it do). Warm the engine up and push the choke in (all the way off). Turn the idle speed screw in until it will run. Take the air cleaner off and peek inside and see if fuel is spraying out of the primary main nozzle (the concentric ring thing in the bore). If so this is bad and it means that either the manifold vacuum is too low to pull enough fuel from the idle port or that the idle port is plugged and can't deliver the fuel.

Make sure that the idle fuel cut off solenoid is working and measure the manifold vacuum. Chack for manifold leaks by spraying liquid carb cleaner around all the connections and seeing if the idle improves. Manifold leaks are pretty common problems on 2Fs.

 

[CliffClaven]

Pin Head,

I have read those articles again and they make some more sense to me now that I've played with the carb a little.

Let me ask you a couple of things;

You say to get the vehicle to run (idle) I want to turn the idle speed screw "in" I'm guessing that is CW so that the spring puts more force on the position it pushes on. Is that correct? So I should turn that screw CW until it will idle by itself? This is when I peek down into the carb and see where the juice is coming from? If I see fuel in the concentric part and my vacuum gauge reads low I have a vacuum issue? Where do I plug in the vacuum gauge, the intake manifold?

 

[Pin_Head]

You say to get the vehicle to run (idle) I want to turn the idle speed screw "in" I'm guessing that is CW so that the spring puts more force on the position it pushes on. Is that correct?

Correct.

So I should turn that screw CW until it will idle by itself?

So that it will run at as low a speed as it can without stalling.

This is when I peek down into the carb and see where the juice is coming from? If I see fuel in the concentric part and my vacuum gauge reads low I have a vacuum issue?

Yes, take a peek. You may need a flashlight. If you see fuel spraying out of the nozzle, then it isn't really idling. It is running off the main jet. This is either due to too much air (a manifold vacuum leak) or too little fuel at the idle port (the solenoid not working or the mixture screw too far in).

Where do I plug in the vacuum gauge, the intake manifold?

Anywhere there is a hole in the manifold that some vacuum tube connects to. (Sorry, I am not that familiar with the FJ60 manifold).'

 

[CliffClaven]

Thanks man! I have an extra (capped) nipple on my gas filter on the intake from doing the desmog I can attach the gauge there.

Just to double check;

Screw closest to the base of the carb is the idle speed and the one a little higher up is the fast idle speed...correct?

 

[2mbb]

So even if the choke cable is pulled, once the engine starts, the choke breaker opens the choke plate about 1/2 way. Once the engine is up to operating temperature, the choke opener, opens the choke plate all the way. At this point, the only thing that is making your engine run fast is that the fast idle screw is holding the throttle plate open a bit.

I would start this way:

1. ensure the idle cut solenoid is working properly. do a search or get the emissions manual to check this.
2. screw the idle mixture screw (the screw next to the valve cover) all the way in (clockwise) until it just seats (don't over tighten). Then turn the screw out two full turns.
3. Unscrew the idle speed screw (counter clockwise) until the point it just stops contact with the tab on the throttle plate shaft. Then screw the idle speed screw in (clockwise) two full turns. You should see the throttle plate shaft rotate open as you do this.

If the engine start and runs, first try adjusting the idle speed screw until you get the idle speed correct. turning the screw clockwise should increase the idle speed, counter clockwise will decrease the speed.

At this point you can start the lean drop method.

 

[Pin_Head]

The idle speed screw goes through the base of the carb and is the one most inside. Its head is angled to the drivers side slightly. The other speed screws are on the linkage.

 

[CliffClaven]

The idle speed screw goes through the base of the carb and is the one most inside. Its head is angled to the drivers side slightly. The other speed screws are on the linkage.

That is what I thought I just wanted to confirm.

Alright guys I think I have a better grasp on this. The FSM kind of assumes you have some understanding of what turning the screws is doing, but now I think I can use my resources I've gathered to get the job done.

2mbb,

I have both the 2F repair manual and the emissions manual. I never realized how the two go hand in hand until now.

 

[2mbb]

The idle speed screw goes through the base of the carb and is the one most inside. Its head is angled to the drivers side slightly. The other speed screws are on the linkage.

Maybe I don't understand your explanation. All the "speed" screws, idle, fast idle and A/C idle up are on the linkage and they all set the position of the throttle plate shaft.

The screw that is on the side of the carburetor that is next to the valve cover (the right side of the carb when sitting in the truck) is the idle mixture screw. This screw threads into the base of the carb and acts like a needle valve to adjust the flow of fuel through the idle circuitl

 

[Pin_Head]

I am not intimately familiar with FJ60 carbs, but on FJ40 carbs up through at least '78 the idle speed screw passes through a hole in the base casting. It is the hardest adjustment screw to see. The fast idle screw etc. are attached to linkage pieces that rotate with the shaft. HTH

 

[Lugal]

Sorry for the dumb question, Cliff, but are you sure that what you're referring to as the "idle mixture" screw really is that? From the factory, that screw is capped with a plug that has to be removed, and even then it's a bit of a bitch to get to. The diagram that 2mbb shows it, but even then I (pretty much a newbie, too) have one hell of a time getting to it.

 

[CliffClaven]

Sorry for the dumb question, Cliff, but are you sure that what you're referring to as the "idle mixture" screw really is that? From the factory, that screw is capped with a plug that has to be removed, and even then it's a bit of a bitch to get to. The diagram that 2mbb shows it, but even then I (pretty much a newbie, too) have one hell of a time getting to it.

Lugal,

I'm 100% sure I know where the mixture screw is. My rig has 225k on it and I'm sure the carb has been rebuild once or twice before I rebuilt it. It was not capped when I took the carb off a couple months ago, but thanks for checking.

I know which screws are which now. I will try and "Reset" everything tomorrow to start from the ground level and take another stab at it.

 

[Lugal]

Good then, it sounds like you'll be in better shape when you try again tomorrow. Listen to what the other guys have to say. Unlike me, they know what they're talking about.

 

[CliffClaven]

Thanks! Thanks to everyone who helps me with my little cruiser hardships.

I'm just about the most impatient person alive right now. I can't wait to be driving in my cruiser soon. If I can't get this thing to run smoothly tomorrow or Sunday I'll take another look at vacuum line placement, but I'm 95% sure I have everything connected properly.

I need to pick up a vacuum gauge as well. I'm also pretty sure my solenoid is working correctly, but we'll find out.

 

[tpc78]

Had a similar problem and my cruiser would only run whit either choke pulled or constantly feeding it gas. I messed with the carb over and over again and could not fix the issue. Turned out to be the solenoid attached to the carb. To temporary remedy the problem I cut the green wire (if i remember correctly) and grounded it. This keeps the solenoid "open" all the time. It runs perfectly now. I did this last summer and have had no problems since. I am just being lazy and have not ordered a new solenoid yet. good luck

 

[CliffClaven]

That's good to know. There are threads about testing the solenoid and I'll check those first I guess. It's always possible that it worked before I rebuilt the carb and now it's not working. In the case that it has failed I will buy a new one. If grounding it out will open it I might do this until the new one arrives, but we'll see. The issue you describe sounds very familiar to me right now.

 

[CliffClaven]

I'm going to resurrect this one! It idles! I'm very happy about this and I'm grateful for all the help I received. Now what is left to do is the lean idle drop procedure and I'll be sitting pretty. I talked to the exhaust shop a few minutes ago and I should have new exhaust on Monday!

I might take it to a different shop if they can get me in tomorrow though.

 

[4runner4ever]

Thanks for this post-very easy to follow. Gotten rid of Carb Cupachabra-for now..

 

[eaj71]

Still a good threaf!

 

[Seth S]

Still a good threaf!

Yep. I’ve been reading it recently too