1984 FJ60 Engine Sputtering, Bucking - FIXED!!! (1 Viewer)

[Landpimp]

that is the vacuum switch and its in the stock location. the diagram makes it look like its someplace else(like carb or manifold)

its been awhile, but I think the vac switch only comes into play during coasting or off the throttle or something like that.........but I will wait to be corrected by someone who knows or remembers better than me

 

[mwebfj60]

Here’s a functional video of the Idle Cut circuit.

 

[Gretsch]

OK thanks for the clarification on switch location. Yes I think you are right. Seems to come into play during decel, which was usually when I have my problems. I should have included the chart in the FSM troubleshooting which kinda goes over what the switch does and when:

Hopefully you can see that. So in a situation where this vacuum switch were faulty and getting stuck somehow on vacuum pressure change, sending a signal to EC to close the ICS and keep it closed, could this perhaps cause my idle issue? Not sure it explains the bucking at hwy speeds, but thought I would throw it out there as a possibility. The ground to carb mod seems to indicate that it works with a good ground and that the EC ground joints on the board could be the culprit here as we have stated. But since it also takes the EC and the EC inputs out of the equation there is no way to tell if its really the EC or something else in the ICS chain.

I think my next step here is to get a test light and run it from the pin on the EC harness plug to the pin on the ICS plug (EC side) to rule out bad wiring. Then if that checks out try and either look for solder breaks on the EC board and re-flow them or find a new EC. Just wondered if this vacuum switch could be the culprit here. Open to feedback on that idea.

 

[Gretsch]

Here’s a functional video of the Idle Cut circuit.

Wow that's great video. Extremely helpful. So I had also read somewhere that the FCS and ICS are actually separate things that have different functions, yet it seems folks use ICS/FCS interchangeably. This video is showing the function of the ICS in the carb (what the light is connected to in the video I believe). Can anyone confirm the ICS/FCS thing?

So it seems that the ICS/EC has a delay in when it closes according to the video. Allows the ICS to remain open between shifts I guess. I think I am going to try this idea on my truck and see how it reacts with the wiring put back to factory. Great video. Thanks for that.

 

[mwebfj60]

Idle Cut Solenoid, Fuel Cut Solenoid. Same thing used interchangeably on here. Proper term ICS.

 

[mwebfj60]

Grounding the ICS takes the vacuum switch and “computer” out of the loop so the ground doesn’t get disrupted. You still have to ensure you have 12V going to it so it remains open the whole time.
This thread has some sleuthing I did on the circuit.

Aisan Decel Fuel Cut Circuit

 

[Gretsch]

OK yes @NeverGiveUpYota was kind enough to alert me to this thread at the time I originally had my issue. I forgot about the video though. The ground thing worked for me at the time so I dropped this thinking I had things licked. I had forgotten about the vacuum switch I guess as its mentioned in your thread. Starting over with learning about this. Thanks for the help. Much appreciated.

 

[Gretsch]

So at the suggestion of @Skeet (thanks again for the help here), I decided to re-flow the plug solder joints on my ECU yesterday to try and end this once and for all. I was a little freaked about the idea of doing this but it turned out easier than thought it would be. Basically you could just touch the soldering iron to each pad on the board and the solder just re-flows. I added a little to help things along as well. I took some photos of before and after doing this and thought I would post them to help illustrate what this looks like in an FJ60 ECU. The broken joints appear as little black rings on the solder cones on the back of the board. Hopefully the below photos show this clearly. When looking at the joints with a magnifying glass, I really could not see them with my eyes. I zoomed into my photo however and could see them better. I don't really know what pin does what here and which one grounds the ICS, but all of mine looked suspect. There are threads already which talk about this issue and saw one that showed what a broken solder joint looks like, but none I could find that shows this in the FJ60 ECU itself. Apologies for the re-post of this has been done before. Hopefully this helps someone understand what folks are talking about when discussing broken solder joints. See below pic of the plug solder joints on my ECU:

Black rings on almost every joint. I looked into this and it seems this is common with any older PCB board setup. After re-flowing the solder things on my ECU looked like this:

No more black circles. I am not an electrical engineer so soldering this, while not difficult, possibly yielded less than professional results (save the soldering critiques please). The best way to do this is to heat the old solder, and suck it up with a solder tool to get it out of the way, then replace with new solder. I just opted to heating and adding solder as mentioned.

So the good news: It does not seem as though I have destroyed my ECU. Even better news: Truck idles now without the ground bypass mod. I am plugged back into factory ICS plugs. Truck runs just like it did with the bypass mod. I drove it around running errands for awhile yesterday afterwards and never had it die on me. Idles perfectly. Now I'll reserve judgment on if this is truly fixed after running like this for a few months as my issue was so intermittent. But hopefully this gets me fixed. Would like to again thank everyone that offered suggestions in this thread. So very thankful to all you guys/gals. What a great community.

 

[NeverGiveUpYota]

Woohoo! Congrats. I do see now the black rings when I zoom in. I actually started a thread on doing this specific fix and the photos a few added weren’t from a 60 but decent enough examples. Guessing you saw that one. I kept meaning to do mine since I have a soldering iron I’m willing to sacrifice (from my wood burning days). Something I might give a shot at now. You bought a roll of lead and flux?

 

[Gretsch]

Thanks. I had a roll of rosin core solder I used. I just mostly melted the existing solder, hit the pad with additional real quick, let it flow, then backed off the heat. Got in and got out. Had to get a new soldering iron though. The one I had is ancient and no longer transfers heat well enough to do something this intricate. New iron has a pencil type tip to localize the heat a bit more than my old one. Hopefully this works out for me. Not sure what I am more happy about, the fact she idles now or that I did not seem to have F'ed up this ECU. The ones I have seen for sale seem pretty pricey for old 80's era circuitry. Having now seen what the ECU really is would have made me sick to have spent that kind of money on it if I had broken mine. Anyway super stoked this seems to have worked. No way I could have figured this out without this forum. Thanks again all.

 

[morganism]

Just a heads up to others doing the soldering, if you use rosin core, you really need to clean the leftovers off with alcohol, even vodka, or one of the "orange" based cleaners

rosin helps "etch" the surfaces to clean em, so solder will stick. If left on, it will continue etching, right thru contact leads....

 

[Gretsch]

Just a heads up to others doing the soldering, if you use rosin core, you really need to clean the leftovers off with alcohol, even vodka, or one of the "orange" based cleaners

rosin helps "etch" the surfaces to clean em, so solder will stick. If left on, it will continue etching, right thru contact leads....

Agreed. This is an important point as leaving that rosin flux etching things can mess it up. I hit mine with alcohol after soldering things up. The photo is just after the soldering so it does not show the cleaned joints.

Again to do this right, de-soldering with a de-soldering tool, and re-soldering is prolly the way to go. I tried using a solder wick to de-solder the leads but it was not working well for me. Some of my joints were also pretty oxidized and de-soldering would have been the best way to make sure all the impurities were removed to ensure a good solder joint. Just adding solder is prolly not the best idea but its working for now. If I run into trouble again I'll probably invest in a de-soldering tool and start over.

 

[knightbreather]

Hey guys, first of all thanks for all of your help in diagnosing and suggesting and in many cases being spot-on! I'm writing in this thread because what seems to have baffled me for a good number of weeks is finally getting to the point where I have no idea what else it could be. To be concise, I'll lay out what I've tried thus far, and what else can be done:

Truck is a 1981 FJ60, PO had it desmogged, and it has a trollhole carb on it (one wire, 12v direct to the FCS wiring harness). Problem is same as what is described above in this thread, and through troubleshooting with what has been suggested, I have managed to get it to mostly idle, but will only do it very reluctantly if without the choke. I'll drive it out, and as soon as we get out on the road, I'll go for maybe a half mile, and it will drop all power and stall- enough time to get it up to 4th gear.

I have tried the green wire 12v direct from battery to FCS wire, checked the fuse on the 10A engine fuse in the dash, pulled it out and started it with the 12v to FCS, the vacuum hose from distributor was incorrectly on the outer nipple (high altitude one) which I moved down closer to the distributor, which is where I'm pretty sure it's supposed to be, grounded the igniter with a separate strap that goes directly to the body as a ground, changed the fuel filter, looked in the glass in the carb to make sure that there is gas in the carb bowl. Lastly, yes- I have taken the gas cap off and tried that, all to no avail...

About the only other thing I can think of is that the fuel pump has gone bad, but from the looks of it, it looks itself almost brand new. I plan to change that on Friday or Saturday- whenever the parts get here.

Is there anything else I am just blatantly missing here?

One thing that comes to mind is this carb doesn't have a ground wire- only one wire coming off the FCS. Any thoughts on that, because I feel like I've literally tried everything...

Thanks in advance guys

 

[wngrog]

Hey guys, first of all thanks for all of your help in diagnosing and suggesting and in many cases being spot-on! I'm writing in this thread because what seems to have baffled me for a good number of weeks is finally getting to the point where I have no idea what else it could be. To be concise, I'll lay out what I've tried thus far, and what else can be done:

Truck is a 1981 FJ60, PO had it desmogged, and it has a trollhole carb on it (one wire, 12v direct to the FCS wiring harness). Problem is same as what is described above in this thread, and through troubleshooting with what has been suggested, I have managed to get it to mostly idle, but will only do it very reluctantly if without the choke. I'll drive it out, and as soon as we get out on the road, I'll go for maybe a half mile, and it will drop all power and stall- enough time to get it up to 4th gear.

I have tried the green wire 12v direct from battery to FCS wire, checked the fuse on the 10A engine fuse in the dash, pulled it out and started it with the 12v to FCS, the vacuum hose from distributor was incorrectly on the outer nipple (high altitude one) which I moved down closer to the distributor, which is where I'm pretty sure it's supposed to be, grounded the igniter with a separate strap that goes directly to the body as a ground, changed the fuel filter, looked in the glass in the carb to make sure that there is gas in the carb bowl. Lastly, yes- I have taken the gas cap off and tried that, all to no avail...

About the only other thing I can think of is that the fuel pump has gone bad, but from the looks of it, it looks itself almost brand new. I plan to change that on Friday or Saturday- whenever the parts get here.

Is there anything else I am just blatantly missing here?

One thing that comes to mind is this carb doesn't have a ground wire- only one wire coming off the FCS. Any thoughts on that, because I feel like I've literally tried everything...

Thanks in advance guys

One wire is normal. 60s are not super easy to desmog. Hard to know if that part is right to advise. Maybe some pics

 

[Gretsch]

Would agree with the above. The only thing I think the single wire does is bypass the emissions computer control of the ICS. With a single wire the ICS is hot (open) as long as the key is on. Normally the ICS is ground switched at the emissions computer. With yours its always grounded at the carb case itself so just needs the hot lead to activate and open. Doesn't sound like this has to do with the ICS to me. You can verify ICS function by maybe rigging up a test light that you can see while driving to the ICS lead to see if it goes off. With your setup the light should be on as long as the key is on. Have you checked for vacuum leaks? Put a vacuum gauge on it to see if the engine pulls vacuum? I would probably forget what the PO did with the desmog and go through the desmog guide yourself to make sure things are properly in place. As @wngrog mentions desmogging one of these is not the easiest thing to do and to get right the first time around. HTH

 

[ceylonfj40nut]

Have you confirmed that the ICS is working. It should click open when hot. You should be able to hear it. Sometimes even if it does click it may not be open. Several folks on Mud have seen this. Sometimes the oring is not seated well or damaged. Did not see you mention these. If you have not physically inspected the ICS, I recommend you do. There are some threads mud. Use the google search in place of the Mud Search function.

 

[Michael Hanson]

Hi, What are your compression numbers? I'd check out your valves. Mike

 

[knightbreather]

Bunch of photos attached here. Yesterday I went over to Napa and picked up an ignition control relay and plugged it in underneath the dash. Seemed to run better and more consistent, and although it still died once on a deceleration pulling up to a stoplight, it didn't do the drop in power completely with my foot to the floor. Going to take it out today for some more test driving. Will check compression numbers next time I get a chance.

Where should this actually plug into? Lead from the distributor cap, not plugged anywhere

This vacuum hose was on the more outer part of the diaphram on the side of the distributor- is it correct where it is placed currently? My understanding was the more outer one was for the higher altitude control?

These wires could stand to be redone completely to make sure they are secure connections, but it does give 12v to the FCS....

 

[Skeet]

I don't know if it makes a difference but the choke breaker is usually connected to a port on the top of the carb and not the manifold.

 

[Gretsch]

Have you confirmed that the ICS is working. It should click open when hot. You should be able to hear it.

I'll second what CD asks above. I didn't see where this was answered and looking at the ICS wiring, it looks pretty dodgy to me. I would make sure that's right before doing anything else. Again, the click does not always mean the thing works. When troubleshooting this on mine, I always heard a click but yet it would run like crap. That's why I suggested hooking up a visible test light so you can see what its doing as you drive. There is a video earlier in this thread that shows what I mean. I would initially shore up those wires and check for the clicking sound. Easiest way is to turn on key and plug and unplug the ICS from the engine bay, although it does not look from your pic like you can easily do that the way its set up.

You are correct that on a stock truck the outer dizzy vacuum diaphragm advance port is the secondary advance that was used for high altitude control via the HAC. The inner advance port should go to the carb Advancer Port on the carb and the outer goes to the HAC on the middle low port (ports arranged in a diamond with the lower middle port of the diamond being for the dizzy secondary advance). Someone will need to check me on this but I think your dizzy vent plug should go up to the aircleaner. There is another vent that should go off to the firewall.

As far as I know this doc is still good for desmogging a 2F. If its not then someone can speak up. I would just run through it if I were you and make sure your truck matches. HTH.