Intermittent Electrical Issue And Random Sputtering (1 Viewer)

[BlackPanzer]

Hello all,

I am having an issue that seems common to FJ60s, the random sputtering issue. Mine is a 1987 FJ60 completely stock with the original US emissions. The DUI distributor is one of the few things that is not stock. After a thorough search of related issues in the tech forums, I discovered that the issue I'm experiencing may overlap with many things. This has been a long journey down a rabbit hole replacing parts, scratching my head, and not going anywhere. I need help.

First the issue- between 1200-2200 RPM the engine seems to sputter. This goes away under load somewhat. I started to experience this about a year ago. About three years prior to that I replaced my stock distributor with a DUI. The problem is very intermittent. One day it is running like a top and then the next it is a herky-jerky ride. Two times I have blown and replaced the control modules in the DUI distributor. I just replaced the entire DUI with another after trying to diagnose the problem and hearing a buzzing electrical noise from around or inside the DUI. This happened after the ground was disconnected. I am guessing that a capacitor in the DUI was keeping things energized. Maybe something was grounding out inside the DUI?

I should also mention these things to alleviate other symptoms:

-The carburetor was recently rebuilt, the fuel is fresh, and is treated with ethanol treatment. I put Startron into it at every fill up.
- The fuel pump is good. It is delivering fuel at idle and under load.
- All fuel filters are replaced with new.
-The intake gasket was replaced.
- The vehicle was smoke-checked for vacuum leaks. There were none.
- Before the first control module blew, the timing would retard under load. I checked the adavance on the DUI replaced the control module with a new one and the symptoms stopped. This seemed to narrow the issue to the DUI... or so I thought.
- The timing is set to stock for an FJ60.
- The plug wires have continuity. I have not checked resistance.
- EGR seems to be working, i.e. not plugged but without replacing it I am 100% sure it is good. Frankly I am tired of replacing parts.

After reading many of the fixes in the forums, I have discovered two more possibilities. One is the tachometer causing this. Maybe it is grounding or shorting out? Do I replace or try to refurbish it? The other is the emission control computer. I am not sure if I should replace it (again, another part replacement) or maybe just disconnect it. Then again I just don't know what is happening. I took it to my club mechanic and even he gave up after going down the same rabbit hole of part replacing and guessing. Any help that you can provide is appreciated. I am tired of this Alice in Wonderland adventure. Thanks.

 

[cwwfj60]

Search for “green wire mod”

related to the tach, ac amplifier signal that can screw with your fuel solenoid on the carb.

 

[OSS]

In my experience at least, random sputtering is often an ignition problem.
After visiting this forum for over seven years, I've got to say that I've never heard anything good about the DUI distributor.
There isn't a single thread here where someone says "it works great, no problems". Maybe some of them do and we don't here about it, but usually it's part of a problem thread.
The typical DUI referenced thread is pretty much like yours: Random mysterious problems that can't be pinpointed.

While your issue may not be the DUI, it certainly is the elephant in the room.

 

[rlocke49]

I recently went down the same rabbit hole, I would recommend unplugging the Tach wire at the distributor and taking it for a ride. That stopped my hesitation entirely. It's a really simple issue to diagnose/rule out if nothing else.
Cheers,

Ryan

 

[BlackPanzer]

Thank you for the advice. I will disconnect the tachometer wire from the distributor. That is the easiest to diagnose.

Dumb question: Is the tach-wire or the gauge grounding out, hence the current drop? Would replacing the tachometer fix the problem too, assuming that is the cause?

 

[rlocke49]

Thank you for the advice. I will disconnect the tachometer wire from the distributor. That is the easiest to diagnose.

Dumb question: Is the tach-wire or the gauge grounding out, hence the current drop? Would replacing the tachometer fix the problem too, assuming that is the cause?

That’s not a dumb question! I would assume if you had a wiring issue it would like just cause the tach to stop working, not interrupt your ignition/fuel since the tach works off of induced voltage like a timing light. I would suspect the tach over the wiring but would need to spend some time with the wiring diagram to better understand it.

 

[g-man]

A partially burned or corroded wire can develop inside a plug wire. You can't see it because it's happening inside the insulation. This can cause random or intermittent firing of a cylinder...ie sputtering. You can get a good continuity test on the wire but when it flexes or moves at all ...lose spark. Did you try flexing the wires as you did the continuity test? Do you have another set of wires you can try? Do you still have the original dizzy that you can try back on?

 

[BlackCat]

2 things- try disconnecting the tach like mentioned, and also try bypassing the EGR valve. Both are quick, easy, and won’t cost you a penny. My EGR gives me all kinds of surging issues when it’s connected. I just bypass it and then reconnect the vacuum lines on my way to emissions, and bypass it as soon as I’m done.

 

[BlackPanzer]

related to the tach, ac amplifier signal that can screw with your fuel solenoid on the carb.

I am not sure I follow this. Thanks for posting. I checked the "green wire mod" and will try it after disconnecting the tach and EGR bypass. If I am understanding this correctly, the tach may be used with an AC amplifier intalled ( presumably increasing the current)? I did not see anything about installing an amplifier. Is there something on this forum for that? The reason I ask is I would still like to have use of the tach... I am a Land Cruiser purist... guilty as charged. If this is not possible well, there are worse things to live with... An update is coming.

 

[cwwfj60]

I am not sure I follow this. Thanks for posting. I checked the "green wire mod" and will try it after disconnecting the tach and EGR bypass. If I am understanding this correctly, the tach may be used with an AC amplifier intalled ( presumably increasing the current)? I did not see anything about installing an amplifier. Is there something on this forum for that? The reason I ask is I would still like to have use of the tach... I am a Land Cruiser purist... guilty as charged. If this is not possible well, there are worse things to live with... An update is coming.

Before worrying about anything simply disconnect the tach wire from your coil. There is two wires coming off the coil that have connectors, I can never remember which one is which, but one is tach and one is distributor I think….anyways one will make your truck die/not start. So unplug one of them and see if you killed the truck or the tach….once you have the right one disconnected (running truck and no tach signal), go drive your truck and decide wether it fixed your issue or not.

Report back and I’ll find a helpful link by then.

 

[BlackPanzer]

Update:

Thank you for all of the help. The tachometer was disconnected with no effect on the sputtering. The EGR was bypassed with no effect on the sputtering. The plug wires were checked for resistance and everything was good. After doing a little more research and looking at a wiring diagram it looked like a lot of things connected to the emission control computer. On a whim, I disconnected it and it seems to work with out the sputtering. I test drove it for over 45 minutes running some errands without issue. I am not sure exactly what is happening but whatever the emission control computer was interferring with, the sputtering seems to be gone. I will do a few more drives to see if this holds. If anyone knows how this little monkey screws with things, please let me know. Maybe it is cracked on the circuit board somewhere and shorting out? I am not sure if I need to replace it, especially if it is running well now. Thanks again. Here is the emission control computer that is located under the left inside kick panel:

 

[BlackPanzer]

Long term update:
I hope this helps contribute to the general knowledge of this thread. It's been about three weeks since my last update. After several long term drives It appears that unplugging the emission control computer (ECC) rectified the sputtering. Looking at the wiring diagram it appears that the ECC may do the same thing as the "Green Wire Mod," but I am not an electrical expert. I am not sure why the distributor was blowing control modules. I suspect that has a lot to do with the old control modules being manufactured in China. The new DUI contains USA made Delco control modules. Therefore it looks like there were a possible two problems.
The DUI distributor appears to not be compatible with the ECC or at the very least may cause future problems when the ECC is functional. Fortunately for me the state I live in does not require emission tests for vehicles over 25 years old. Again, hopefully this helps someone encountering the same problem. All the best.

 

[Gretsch]

Looking at the wiring diagram it appears that the ECC may do the same thing as the "Green Wire Mod," but I am not an electrical expert.

Green wire mod involve permanently grounding the ICS at the carb such that it is always energized when the key is on. Normally the EC controls the operation of the ICS at the carb by ground switching it as needed. I believe the ICS is there to prevent engine run on after shutoff but I think it also prevents unburned fuel from flowing into the exhaust system on decel, potentially damaging the cat in the process. There is a vacuum switch that the EC gets its input from I believe for ground switching on and off the ICS. Sometimes the connectors on the PCB for the ICS ground control can get worn after 30 years of use and can actually crack and work intermittently. I had a sputtering issue when I first got my truck. Not exactly the same as yours but similar. Mine would actually cause the engine to shut off at idle and hammer the truck at highway speeds by shutting it off completely. Would violently buck like crazy which happened on the drive home from purchasing it. Not a good start. I tried the ICS ground mod (green wire mod?) and it fixed my issue. I too am a purist so I wanted the EC in place. So I then decided to try and reflow the solder joints on my EC PCB. This is the part on the EC where the plug for the wiring harness is connected to the PCB itself. There is a line of solder joints there where I reflowed the solder. That solved my sputtering problem. There are other things the EC does which you might still want done. While it might solve your issue, I am not sure what else simply unplugging it does and I am actually surprised it runs at all with it unplugged like that. Maybe something to do with the DUI setup. Some shots of the EC repair:

You can see the black rings on the solder joints as they crack with age and repeated heat/cool cycles.

YMMV here but you might just think about trying the grounding mod with the EC plugged back in and see if that fixes your stuff up. If it does then you can try the solder re-flow. If not then continue along as you have them. Rather than cutting the wire at the ICS, I just created some jumper wires to plug onto the pins in the ICS plug so I could easily put it back stock after testing. Or if things are working well for you maybe just leave well enough alone. HTH.

Edit: Quote from our resident expert Jim C. found in another thread:

The emissions computer runs the fuel cut solenoid on the carb (amongst other things). Just disconnecting it will kill the idle and make it run like poo generally.

If disconnecting the box makes the truck run perfect, then the box is not the problem.

 

[MoaByte]

My HEI was grounding through the shaft causing all kinds of chaos. It cooked the lube into gum and the advance was sticking.. I replaced it under warranty and it happened again.
The solution was simple. Tear down, clean and re-lube it with high temp wheel bearing grease. Pack the reservoir with grease and coat the rotor screws with dielectric grease. If you pull the dizzy, and the shaft doesn't spin easy, you found the problem or if your advance doesn't snap back.

 

[BlackPanzer]

Sometimes the connectors on the PCB for the ICS ground control can get worn after 30 years of use and can actually crack and work intermittently. I had a sputtering issue when I first got my truck. Not exactly the same as yours but similar. Mine would actually cause the engine to shut off at idle and hammer the truck at highway speeds by shutting it off completely. Would violently buck like crazy which happened on the drive home from purchasing it.

Gretch, this happened a few times, but it was intermittent. This happened both with the DUI and OEM distributor it replaced. At one point the bucking and sputtering was so bad I had it towed home. The OEM distributor was replaced with the DUI about four years ago, due to a worn cam and being suspect of causing the sputtering then. I went back to my notes from the install of the DUI and saw that the EC was disconnected at the time of the DUI install. Somehow it was reconnected. The truck ran great for a while with the EC disconnected. I'm not sure how it was reconnected but it may have been from troubleshooting with a buddy of mine trying to diagnose the sputtering when it returned. I guess we forgot it was plugged in. As part of my testing I did re-plug the connector into the EC module and within a minute of doing so the sputtering/bucking started and the acceleration flat-spot returned. To me this confirmed the EC is the problem.

BTW, I did disconnect and reconnect the ICS (green wire mod). The engine quit when the ICS was dissconnected. I did not ground it with the a jumper wire because it seemed to be working, cutting out when the power was off (stopping the dieseling affect, which at the time I thought was its purpose along with cutting fuel on deceleration). Now, I am wondering if disconnecting EC is just a band aid. The point is the symptoms were similar to yours. I will see about re-soldering the EC and see what that does. I too am a purist. But then there is this little nugget from Jim C. "If disconnecting the box makes the truck run perfect, then the box is not the problem." Well, now I don't know... Is it the EC or the ICS (green wire mod)? The truck is running well now with the EC disconnected.

You bring up the point of DUI setup. I am not sure how this fits in to the equation, other than bypassing the EC with the DUI seems to make the engine run better. I'll update once the EC is re-soldered and reconnected. I figure, I always disconnect it again if the sputtering returns. Thank you all.

 

[Gretsch]

You bring up the point of DUI setup. I am not sure how this fits in to the equation, other than bypassing the EC with the DUI seems to make the engine run better.

I have no knowledge of whats needed to make that DUI run on these trucks. Maybe some kind of timing/advance adjustments? Definitely don't want to take you down yet another rabbit hole with this, but I can tell you that when I had this sort of issue, disconnecting and reconnecting the ICS always got it to click and caused the engine to die when disconnected while idling. So when testing it, it always seemed to work as to make me think it was not my issue. Yet when I would drive it it would sputter. I wasted about 4 months not doing the ICS ground open mod. As soon as I did my issues when away.

Is it the EC or the ICS (green wire mod)? The truck is running well now with the EC disconnected.

I am not sure how disconnecting the EC would allow this truck to run. AFAIK, disconnecting it would not allow the ICS to open at all starving the truck of fuel. Maybe someone can provide additional information on how this is possible. I'd have to stare at the diags to understand. Unplugging the EC never once occurred to me. Again maybe there is something specific to the DUI setup that allows this. I am not sure. My symptoms do not seem to be exactly the same as yours and your setup is obviously different than mine. But before I would go about re-soldering anything, I would verify that re-soldering would fix anything by first bypassing the EC for ICS control by hard grounding it to the carb body. That's all the re-soldering really does is fix the grounding which you would do by doing the hard ground open mod. Right now we don't even know if the ICS has anything to do with your problem and the ground open mod is an easy way to see if it helps your situation. Air, fuel, spark.....right now we don't even know which one is busted. Mine turned out to be fuel by way of an electrical issue. Your EC could just be broken. Since your truck is running well without the EC, maybe skip doing anything and have fun driving your well-behaving 60 series.