GCC-spec 3F engine won’t idle (1 Viewer)

[beanz2]

So I rebuilt my 3F carburetor this weekend. Pinhead’s videos on YouTube was quite helpful, almost as much as the factory manual. The problem is, now after the rebuild, the cruiser would not idle.

This is a GCC-spec FJ75 with a GCC-only idle speed screw, which is made so that it cannot be adjusted without an SST. There seems to be a spring loaded aluminum sleeve covering the idle speed screw, but the screw itself has no slot or anything else that I can grab to turn it.

The aluminum sleeve you see at the base of the carburetor is the one I’m talking about. The screwhead or whatever underneath is completely smooth and domed.

I had contemplated removing the contraption while I was rebuilding it, but I figured since I did not mess with the adjustment, it would be fine.

Question for you guys familiar with the 3F, especially GCC spec once, if I were to Dremel the sleeve off, would I find underneath a regular screw that I can adjust with ordinary tools?

I’m also wondering if during the rebuild if I somehow messed up the idle circuitry, but I thought I did a thorough job of blowing compressed air through all the carb passages.

Thank you in advance.

 

[Combat Wombat]

It is a little different that what I have seen here in Aus, but it sure looks like a tamper proof device
One solution could be to replace it with a new screw, and keep the factory spec one for if you need to have a EPA inspection
2F 3F Carburetor Idle Adjustment Screw for Land Cruiser FJ40 FJ55 FJ60 FJ62 70 Series FJ80 - https://www.cityracerllc.com/products/2f-3f-carburetor-idle-adjustment-screw-for-land-cruiser-fj40-fj55-fj60-fj62-fj80

 

[beanz2]

Much appreciated, Combat! I'm thinking I may just get the idle screw.

No worries about our EPA. That part was only a requirement in Saudi Arabia LOL

 

[Bardiya]

That is the idle fuel mixture screw.

You can:

1) Use the appropriate Toyota Special Service Tool to make adjustments to your current screw
2) Replace with user adjustable idle mix screw
3) Break the head off the anti-tamper screw, grind provisions for a flat-head screwdriver, and turn it to adjust (GCC method)

 

[beanz2]

Thanks, Bardiya. I have the carb on a bench now and after work I’ll see how the tamper proof idle adjustment screw is secured. Since I have a replacement screw on order thanks to Combat Wombat, I can see what I need to do with this one. I’m not averse to doing what you suggest.

 

[prwillard2]

3) Break the head off the anti-tamper screw, grind provisions for a flat-head screwdriver, and turn it to adjust (GCC method)

Sad that this is the way most of this stuff works in GCC areas.

Hope you get it figured out @beanz2

 

[Honger]

You in the Phoenix area by chance @beanz2? I've got the SST...

 

[mattressking]

Since the mixture screw is the same setting from factory and you can't get it to idle, something was installed/setup incorrectly during rebuild. I wouldn't recommend chasing the mixture screw as the factory setting will be more than sufficient to have the truck run.

Items to check before you waste time with mixture screw:

1. If the truck does not idle - it will turn over and fire up, but not maintain idle? Please clarify. If it does start but not idle, what happens if you add choke to the engine - will it help?
2. Is the Fuel Cut Solenoid clicking repeatedly when key is cycled on/off?
3. Is fuel filling the bowl and at the middle of sight glass? If no visible line you aren't getting any fuel OR you are overfilling and flooding the carb.
4. When you open the primary butterfly, does the accelerator pump spring a clean line into the primary venturi?
5. How much did you turn the idle SPEED screw clockwise(not mixture screw) ? It needs to contact and add roughly 1-1.5 turns for baseline starting.

Based on your carburetor photos, it appears your carb base is VERY wet (with what I assume to be fuel) which to me means you are leaking fuel and it is causing your issue. Please inspect and return back with findings. Not sure why else the base would be glossy, they don't look that clean unless they are stripped and coated with some sort of clear.

 

[beanz2]

Since the mixture screw is the same setting from factory and you can't get it to idle, something was installed/setup incorrectly during rebuild. I wouldn't recommend chasing the mixture screw as the factory setting will be more than sufficient to have the truck run.

Items to check before you waste time with mixture screw:

1. If the truck does not idle - it will turn over and fire up, but not maintain idle? Please clarify. If it does start but not idle, what happens if you add choke to the engine - will it help?
2. Is the Fuel Cut Solenoid clicking repeatedly when key is cycled on/off?
3. Is fuel filling the bowl and at the middle of sight glass? If no visible line you aren't getting any fuel OR you are overfilling and flooding the carb.
4. When you open the primary butterfly, does the accelerator pump spring a clean line into the primary venturi?
5. How much did you turn the idle SPEED screw clockwise(not mixture screw) ? It needs to contact and add roughly 1-1.5 turns for baseline starting.

Based on your carburetor photos, it appears your carb base is VERY wet (with what I assume to be fuel) which to me means you are leaking fuel and it is causing your issue. Please inspect and return back with findings. Not sure why else the base would be glossy, they don't look that clean unless they are stripped and coated with some sort of clear.

You in the Phoenix area by chance @beanz2? I've got the SST...

I appreciate the offer, Honger. But I’ve bubba’ed the tamper proof sleeve and added a slot to the screw head. Just as the replacement idle mixture screw came in from City Racer…

 

[beanz2]

Since the mixture screw is the same setting from factory and you can't get it to idle, something was installed/setup incorrectly during rebuild. I wouldn't recommend chasing the mixture screw as the factory setting will be more than sufficient to have the truck run.

Items to check before you waste time with mixture screw:

1. If the truck does not idle - it will turn over and fire up, but not maintain idle? Please clarify. If it does start but not idle, what happens if you add choke to the engine - will it help?
2. Is the Fuel Cut Solenoid clicking repeatedly when key is cycled on/off?
3. Is fuel filling the bowl and at the middle of sight glass? If no visible line you aren't getting any fuel OR you are overfilling and flooding the carb.
4. When you open the primary butterfly, does the accelerator pump spring a clean line into the primary venturi?
5. How much did you turn the idle SPEED screw clockwise(not mixture screw) ? It needs to contact and add roughly 1-1.5 turns for baseline starting.

Based on your carburetor photos, it appears your carb base is VERY wet (with what I assume to be fuel) which to me means you are leaking fuel and it is causing your issue. Please inspect and return back with findings. Not sure why else the base would be glossy, they don't look that clean unless they are stripped and coated with some sort of clear.

I think you’re right that I messed up something in the rebuild. Comments below.

It started and ran, but won’t idle. I did not remember of checking the fuel solenoid. I will do that when I get back.

Choking the engine did not help at all. It ran the same with it open or closed. The fuel level was visible within the window, although it was maybe about 1/8 inch higher than before. I’ll play with the float adjustments again. I also did not check the accelerator pump stream and I left the idle speed screw unchanged.

As the Keyster rebuild kit did not come with base plate gaskets, I took a shortcut and did not separate the plate from the carb body. My bad. Now I have the necessary gaskets on hand, unfortunately I have to leave town for business.

The iron carb base started to rust when took it out the ultrasonic cleaner, so I applied a rust inhibitor to it, making it look shiny. I do not think there is an external leak as I would have smelled gasoline right away. But, there is indeed some internal leak in there somewhere because after it sat overnight, the carb bowl emptied and the primary barrel was full of gas.

I really appreciate your input. I’ll get back to it next week.

 

[Combat Wombat]

I have been attempting to sort my 3F out, and found the following:

• Vac Lines, were total mayhem, things disconnected and not on the right port etc. The fuel vapour routing is what I'm struggling with currently.

• The tiny circle rubber gasket that seals the Secondary Vacuum diaphragm body to the carb was split and perished. This made for an annoying rough idle and lack of power on acceleration.

• The diaphragm to my distributor advance was split, and that also added to rubbish idle and low power.

• My fuel float level is slightly low. Apparently there is a 'tuned float level' that is better than the factory manual settings. (I am still to check) Secret Asian Carb Float Setting

• The fuel idle screw had debris and a layer of caked oily/fuel residue (will clean up with a scotch pad) hopefully it will seat better once clean.

• Lastly, I am still to check ALL the fuel filters, not just the big one but also tank pickup, and I think a small one on the carb fuel inlet itself.

But a vac leak, is almost nearly always the issue. Hope you find yours before I do!

 

[beanz2]

Thanks again, Combat.

Mattressking is right, the culprit turned out to be the idle solenoid. It definitely was not clicking with 12V applied to it. A 2F solenoid from CityRacer.com fixed the issue.

Here is the bubba’ed GCC-spec idle mixture screw. At first, I tried to split the sleeve into two, but soon I realized that there is a part that goes all the way to the shaft that would make it impossible to Dremel off. Therefore, I just cut off the part that covered the blank screw head. I then cut a slot for a screwdriver:

Even though I did end up buying the aftermarket idle mixture, screw from CityRacer, I ended up not using it.

 

[beanz2]

So she runs! Much smoother than before the carburetor rebuild:


Still far from perfect, but the engine sounds much happier to rev and idle.
I’m not sure if I want to tackle valve adjustments, but she sounds like she needs it.