FJ40 2F Engine Idle Issue, not the usual fix, ideas?

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i see ONLY 1 wire coming from your device side 21062-61060 fuel cut solenoid green connector ?


if you or a PO installed a single wire Varity or this wire has been severed ?

if im correct , this may be a smoking gun and eazy peezy to remedy with the correct replacement parts above i mention to confirm and verify first ?




View attachment 3050193
Thank you for the reply, there are two wires, one is hidden by the angle. The unit energizes when the ignition is turned on, and stays energized as confirmed by a voltmeter at the leads.
 
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One thing these vehicles never came with is a vacuum gauge. I know you said you tried propane method but by having a gauge in you field of view when driving can say a lot. To me without one always kept me guessing.
Thanks Matt, I have a vacuum gauge, but was not sure what vacuum is typical at higher rpm (since it won't idle). What would you expect to see at a higher rpm? And where would you connect to take the reading?
 

ToyotaMatt

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Thank you Matt, the replacement unit looked nearly identical (but with a different connector so required splicing), but I'm not opposed to changing it again. The old one did 'click' when energized, as does the replacement. It continues to be energized when running, confirmed by a voltmeter at the leads.


By chance did u apply anything of a lube on the tiny spaghetti 🍝 o ring ?

Oil

Grease

Vassiline

Do electric stuff ?


If u did not and spun it in dry as a bone


It has a high likley hood of tearing and not making a. Seal as required


I would remove it to confirm and verify if zero lube was applied as a out line above ?

If it’s intact then lube and re install


I hope this helps ?

Matt
 
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Thanks Matt, I have a vacuum gauge, but was not sure what vacuum is typical at higher rpm (since it won't idle). What would you expect to see at a higher rpm? And where would you connect to take the reading?

I connect mine using a TEE to a vacuum line going to the intake. A gas engine vacuum is max at idle and as you accelerate it goes down. Pretty simple, but tells a lot.



 

Pighead

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And where would you connect to take the reading?
I connect mine right to the intake manifold

20220705_195049.jpg
 
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An update...
We finally had some time to implement some of the great suggestions, and decided to start with the fuel cutoff solenoid. We removed and checked it for operation, no problems observed when connected directly to the battery. The seal at the end of the tip looked good. To verify it was getting power when running, I connected a voltmeter directly to the plug. We found that the voltage would fluctuate each time the ignition was turned on. It varied from 5.8 volts to 11.9 volts, leading us to believe there is an issue with the emissions computer.
When we run a ground wire directly to the negative side (white wire) of the fuel cutoff solenoid, it energizes (even when the ignition switch is turned off).
Is this normal (solenoid is controlled by switching negative on and off)?
Even with the fuel cutoff solenoid energized, the engine still won't idle well.
Could a bad emissions computer be the cause of the idle issue, even with the fuel cutoff solenoid energized?
Many thanks for the help and suggestions!
 

Engineer8000

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Your original post said you had an 82, so yes the FCS is controlled by the emission computer. There is a transistor in there that grounds the neg side of the FCS at pin 12 of the emission computer.
 

Engineer8000

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The 81+ computer controls the EGR VSV, FCS, and two air Injection VSVs depending on the inputs. I'm not sure the AI or EGR can cause the idle issue and you took the FCS out of the picture. One thing that comes to mind tho is the computer switching VSVs, maybe it is switching in a vacuum leak?
 

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I checked the emission manual for 81+, it says the EGR valve can cause rough idle. I didn't see that mentioned above anywhere. There is a pretty good troubleshooting guide in the manual. There is a PDF of that manual floating around on the web if you don't have one.
 

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An update...
We finally had some time to implement some of the great suggestions, and decided to start with the fuel cutoff solenoid. We removed and checked it for operation, no problems observed when connected directly to the battery. The seal at the end of the tip looked good. To verify it was getting power when running, I connected a voltmeter directly to the plug. We found that the voltage would fluctuate each time the ignition was turned on. It varied from 5.8 volts to 11.9 volts, leading us to believe there is an issue with the emissions computer.
When we run a ground wire directly to the negative side (white wire) of the fuel cutoff solenoid, it energizes (even when the ignition switch is turned off).
Is this normal (solenoid is controlled by switching negative on and off)?
Even with the fuel cutoff solenoid energized, the engine still won't idle well.
Could a bad emissions computer be the cause of the idle issue, even with the fuel cutoff solenoid energized?
Many thanks for the help and suggestions!


I am going to take a T-TEN leap here and diagnose your problem as a BAD ignition electrical key 🔑 switch ….

The low and variety of voltage and low spikes is suggests to me the rotary copper contacts , springs , and balls are worn and need a new one

This switch directly energizes the FCS through and via the black wire / w yellow tracer stripe ,

You should also update / and upgrade to a 2 wire polarized 8/80 -later
this will eliminate the searching for a ground issue I know for a fact you have going on at well …


 
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I checked the emission manual for 81+, it says the EGR valve can cause rough idle. I didn't see that mentioned above anywhere. There is a pretty good troubleshooting guide in the manual. There is a PDF of that manual floating around on the web if you don't have one.
Thank you, checking into the EGR next (that would make sense if exhaust is getting pushed into the intake).
 
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I am going to take a T-TEN leap here and diagnose your problem as a BAD ignition electrical key 🔑 switch ….

The low and variety of voltage and low spikes is suggests to me the rotary copper contacts , springs , and balls are worn and need a new one

This switch directly energizes the FCS through and via the black wire / w yellow tracer stripe ,

You should also update / and upgrade to a 2 wire polarized 8/80 -later
this will eliminate the searching for a ground issue I know for a fact you have going on at well …


Thank you, do you think this could still be the case, since this is a 1982 FJ?
 

ToyotaMatt

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Thank you, do you think this could still be the case, since this is a 1982 FJ?


Absolutely 100% Yes , it could be a very very likely cause , FCS's / Fuel Cust Solenoids do fail , especially if original to the truck or a single wire version too .....

since you have a 1982 , is it a USA spec. or a NON_USA import ?

reply back on this particular detail and be accurate on your tech here too Please



1658015206478.png
 

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If the ICS you used is one of those $20 CCP units, they don't always work so well. Some do, some don't. If you have the original ICS test it for clicking. If it's working, you might try and swap it back in.

Also, something that I've seen a few times in FJ60s (you have the same carburetor), is when the 35 year old ICS is removed, the bits of the old brittle O-ring from the tip of the nozzle get stuck in the bore, and clog the circuit when the new ICS is threaded in.

You could remove the ICS and try spraying come carb cleaner into the hole, sticking the pipe in to try and dislodge any crap. If the circuit is clear, I think you should see some discharge out the idle circuit port looking down the throat of the primary barrel.
 
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If the ICS you used is one of those $20 CCP units, they don't always work so well. Some do, some don't. If you have the original ICS test it for clicking. If it's working, you might try and swap it back in.

Also, something that I've seen a few times in FJ60s (you have the same carburetor), is when the 35 year old ICS is removed, the bits of the old brittle O-ring from the tip of the nozzle get stuck in the bore, and clog the circuit when the new ICS is threaded in.

You could remove the ICS and try spraying come carb cleaner into the hole, sticking the pipe in to try and dislodge any crap. If the circuit is clear, I think you should see some discharge out the idle circuit port looking down the throat of the primary barrel.
The replacement fuel cutoff could be a lower quality replacement. The old one does still work though, the O-ring is intact, but does show some minor signs of cracking.
We only replaced it to eliminate it as the cause of the idle issue.
 
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Absolutely 100% Yes , it could be a very very likely cause , FCS's / Fuel Cust Solenoids do fail , especially if original to the truck or a single wire version too .....

since you have a 1982 , is it a USA spec. or a NON_USA import ?

reply back on this particular detail and be accurate on your tech here too Please



View attachment 3060860
It's a USA spec, with the factory high altitude setup. All the emissions components (and there are a lot of them) are in place and connected.
We'll be taking a vacuum reading next, currently waiting on a tachometer to arrive (as we want to determine vacuum at the lowest possible rpm that it's fairly smooth at and share the results).
 

ToyotaMatt

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It's a USA spec, with the factory high altitude setup. All the emissions components (and there are a lot of them) are in place and connected.
We'll be taking a vacuum reading next, currently waiting on a tachometer to arrive (as we want to determine vacuum at the lowest possible rpm that it's fairly smooth at and share the results).


I like your technical and practical approach step by steps ,


Your on target 🎯 with your first 2 u mention above …

Timing being out will affect your vacuum in the most drastic ways possible so make darn sure u set it to the stainless steel BB per the FSM

And only then final finite adjust via a high quality vacuum guage hooked up directly to your intake manifold

Not the carb base or any other source to be klear here

This the prescribed recipe for sucses

Then once you have dialed the timing and base idle and fast idle also don’t forget …

Transition to the FCS , and confirm and properly diagnose that ..

I have personally had more then one original fcs provide a solid clicking sound a touchy freely click sensation when hand ✋ held , yet still be a failed faulty part at the end of the day …

Good luck 🍀 your on the right path here I feel …


Matt
 

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