Fuel delivery to Carb! (1 Viewer)

[Gretsch]

Possible you had some trash in there blocking things up I guess. Glad its working. Hope it keeps up. GL.

 

[LandoNick]

Possible you had some trash in there blocking things up I guess. Glad its working. Hope it keeps up. GL.

I just read through your whole 8 paged "fixed issue". seems like its done and you get through but then it rears its head again. I have had the sound to carb for a bit. I need to read through the fix again. computer board was that the ultimate fix? the reflow

 

[Gretsch]

computer board was that the ultimate fix? the reflow

For me and my ICS issue yes that was the fix. I basically did the ICS ground mod to ensure indeed my issue had anything to do with the ICS. After my issues went away with Emissions Computer ground mod bypass, I knew I was looking in the correct place. I could have left the ground mod in place, but there is some benefit to having the ICS solenoid controlled by the EC circuit board. The system is designed to prevent not only run on after engine shutoff but preventing unburned fuel from entering the exhaust system on decel as well. As I mentioned, it took a long time to figure things out. But have never had a single issue like that since doing the solder re-flow.

I don't know if my ICS symptoms were exactly like yours. When on the highway and the solenoid would close, it was like hitting a brick wall at 65MPH. Very violent situation as the engine would try and die and catch and run again while the truck was careening down the road. I mentioned this earlier in your thread about the click test. To me its not useful unless your solenoid is completely broken. When it works intermittently, it didn't help me at all. It always clicked which wasted a lot of time for me looking elsewhere. The better test for me was when the truck would idle correctly, was to unplug the ICS to mimic what it does when the bucking starts. The symptoms were exactly the same when I unplugged it so I knew I must be getting close.

That said, the big issues for me with my ICS troubles were:

1. The violent bucking at speed
2. Engine would die when coming to a stop at a light.
3. When the engine did this, if I pulled choke before it actually died, the engine would come back to life
4. When the engine would try and die, if I gave it gas, I could save it from dying. Even the AC idle up would keep it from dying.

So I have the ground to the body of the carb. The solenoid clicks when I unplug then plug back in.

You mention you have already done the ground mod bypass and your symptoms remained so not sure if your problem has anything to do with the ICS.

Hopefully it keeps working for you. HTH.

 

[LandoNick]

For me and my ICS issue yes that was the fix. I basically did the ICS ground mod to ensure indeed my issue had anything to do with the ICS. After my issues went away with Emissions Computer ground mod bypass, I knew I was looking in the correct place. I could have left the ground mod in place, but there is some benefit to having the ICS solenoid controlled by the EC circuit board. The system is designed to prevent not only run on after engine shutoff but preventing unburned fuel from entering the exhaust system on decel as well. As I mentioned, it took a long time to figure things out. But have never had a single issue like that since doing the solder re-flow.

I don't know if my ICS symptoms were exactly like yours. When on the highway and the solenoid would close, it was like hitting a brick wall at 65MPH. Very violent situation as the engine would try and die and catch and run again while the truck was careening down the road. I mentioned this earlier in your thread about the click test. To me its not useful unless your solenoid is completely broken. When it works intermittently, it didn't help me at all. It always clicked which wasted a lot of time for me looking elsewhere. The better test for me was when the truck would idle correctly, was to unplug the ICS to mimic what it does when the bucking starts. The symptoms were exactly the same when I unplugged it so I knew I must be getting close.

That said, the big issues for me with my ICS troubles were:

1. The violent bucking at speed
2. Engine would die when coming to a stop at a light.
3. When the engine did this, if I pulled choke before it actually died, the engine would come back to life
4. When the engine would try and die, if I gave it gas, I could save it from dying. Even the AC idle up would keep it from dying.



You mention you have already done the ground mod bypass and your symptoms remained so not sure if your problem has anything to do with the ICS.

Hopefully it keeps working for you. HTH.

I think it was a fuel delivery issue, I guess the ics would fall into that category. A carb guru here on mud and Instagram was sure it was timing. After I replaced the push rod cover gasket. Is when it started, but not right away. I drove for a couple of miles without issue. So I think it was timing, it wouldn’t have started or it would have ran terrible.
I’m not confident that you can be so slightly of timing and it idle and drive fine, then all the sudden fall on its face.

The intermittent thing I couldn’t wrap my head around. It would start and idle in my driveway. Then when I drove it would start hesitating and bucking. Sometimes sooner in driving and sometimes later. Then after the last stab of the dizzy. It ran fine with multiple drives around the block.

When it runs good I will unplug it and see if that mimics the symptoms. Also the ics mod you did when the plug was apart and you had other wires in place. What was that? And I pulled the computer. I didn’t really know what I was looking for but maybe you can see something that I can’t.

 

[Gretsch]

So I think it was timing, it wouldn’t have started or it would have ran terrible.
I’m not confident that you can be so slightly of timing and it idle and drive fine, then all the sudden fall on its face.

I wouldn't think timing would be an issue here but wouldn't go against any of the mud carb gurus thoughts there. I have always seen folks with timing issues not able to get the engine started or run reliably. When they run terrible due to timing, they always run terrible not run terrible intermittently. But again someone smarter than me can chime in on that. All sorts of timing possibilities I guess. The fact the dizzy was what was touched would lend itself to the timing idea however. Thats gotta be right for any chance to fix the rest of it, so good to make sure its in place.

The intermittent thing I couldn’t wrap my head around. It would start and idle in my driveway. Then when I drove it would start hesitating and bucking

I feel your pain here. Mine would run great for months, I would think it was fixed, and then it would come back. It sucked. Took maybe a year for things to get figured out. Went down all the same rabbit holes you have. "Maybe its this, maybe its that". If I am honest, a lot of my delay with fixing it was a combination of fear of breaking my then new to me vintage truck, and not knowing enough about it at the time. You don't seem to have that same fear OP so you will likely have this sorted much sooner than I did.

Also the ics mod you did when the plug was apart and you had other wires in place. What was that?

When I did my mod, rather than cutting the factory wiring to ground it, I made it temporary by just jumping the two plug ends together. I would then just jump straight across the hot side to the hot on the solenoid end using a wire and some spade connectors that fit the spade terminals on the plugs. I would then ground the solenoid side from the solenoid plug to the carb body using the same method. Maybe those are the wires you are talking about?

On the EC itself, the solder issue is in the solder joints for the plug that the wire harness from the truck gets plugged into on the EC. Mine had distinct black rings around the solder joints indicating a break in the joint. You have to get pretty magnified to detect the breaks. I don't really see that in your pic. At the time, I didn't fuss with finding the specific joint for the FCS and just repaired any of the joints I thought might be suspect. Diagram may help you find and check the specific pin on the plug for the FCS/ICS:

Again all that said, if you have grounded the ICS to the carb, you are already bypassing the EC anyway. If things still have an issue even after doing that, then not sure that's your issue. To be clear, the ground mod fixed things for me, just as well as the EC re-solder. If its not fixing it for you, then its likely something else causing your problem.

I think I asked this before, does pulling choke when this happens do anything for you to save the dying engine?

 

[LandoNick]

I wouldn't think timing would be an issue here but wouldn't go against any of the mud carb gurus thoughts there. I have always seen folks with timing issues not able to get the engine started or run reliably. When they run terrible due to timing, they always run terrible not run terrible intermittently. But again someone smarter than me can chime in on that. All sorts of timing possibilities I guess. The fact the dizzy was what was touched would lend itself to the timing idea however. Thats gotta be right for any chance to fix the rest of it, so good to make sure its in place.



I feel your pain here. Mine would run great for months, I would think it was fixed, and then it would come back. It sucked. Took maybe a year for things to get figured out. Went down all the same rabbit holes you have. "Maybe its this, maybe its that". If I am honest, a lot of my delay with fixing it was a combination of fear of breaking my then new to me vintage truck, and not knowing enough about it at the time. You don't seem to have that same fear OP so you will likely have this sorted much sooner than I did.



When I did my mod, rather than cutting the factory wiring to ground it, I made it temporary by just jumping the two plug ends together. I would then just jump straight across the hot side to the hot on the solenoid end using a wire and some spade connectors that fit the spade terminals on the plugs. I would then ground the solenoid side from the solenoid plug to the carb body using the same method. Maybe those are the wires you are talking about?

On the EC itself, the solder issue is in the solder joints for the plug that the wire harness from the truck gets plugged into on the EC. Mine had distinct black rings around the solder joints indicating a break in the joint. You have to get pretty magnified to detect the breaks. I don't really see that in your pic. At the time, I didn't fuss with finding the specific joint for the FCS and just repaired any of the joints I thought might be suspect. Diagram may help you find and check the specific pin on the plug for the FCS/ICS:

View attachment 3083136


Again all that said, if you have grounded the ICS to the carb, you are already bypassing the EC anyway. If things still have an issue even after doing that, then not sure that's your issue. To be clear, the ground mod fixed things for me, just as well as the EC re-solder. If its not fixing it for you, then its likely something else causing your problem.

I think I asked this before, does pulling choke when this happens do anything for you to save the dying engine?

If the stumble happens again I will pull the choke to make sure! The problem to is that I don’t drive it after each little thing I adjust or fix. Then I don’t know really if there was a “solve”.

To be honest I am very nervous, anxiety ridden, feel like I’m never going to figure it out.

 

[Gretsch]

To be honest I am very nervous, anxiety ridden, feel like I’m never going to figure it out.

Fear not my friend. You will get it sorted. For me this was the first thing I had to tackle on mine. Happened on the drive home from purchasing it. That was some fun. Lots of "what have I done" second-guessing questions. Thought I would never get this figured out either. Just keep in mind for these old trucks, its all part of the deal. Everyone thinks they are so reliable because of their reputation. At 30+ years old, they are only as reliable as you make them. If you have a reliable truck, then its credit to the effort maintaining it. The engineering is great. But all of them need some help now and again. You can't get mad at a 60 series for needing some periodic assistance. HTH.

 

[LandoNick]

Fear not my friend. You will get it sorted. For me this was the first thing I had to tackle on mine. Happened on the drive home from purchasing it. That was some fun. Lots of "what have I done" second-guessing questions. Thought I would never get this figured out either. Just keep in mind for these old trucks, its all part of the deal. Everyone thinks they are so reliable because of their reputation. At 30+ years old, they are only as reliable as you make them. If you have a reliable truck, then its credit to the effort maintaining it. The engineering is great. But all of them need some help now and again. You can't get mad at a 60 series for needing some periodic assistance. HTH.

Did you have back firing when it was stumbling and hesitating? I would have to get her the throttle and clutch to keep it going.

 

[Gretsch]

Never really had backfiring with my issue. Choke out would save the engine from dying, giving it gas would save the engine from dying. Anything other than just idle would save it. But as I mentioned, it would also do this hard bucking while at highway speeds which is giving it fuel. HTH.

 

[LandoNick]

Never really had backfiring with my issue. Choke out would save the engine from dying, giving it gas would save the engine from dying. Anything other than just idle would save it. But as I mentioned, it would also do this hard bucking while at highway speeds which is giving it fuel. HTH.

Went and started the cruiser. Started just fine. Choke out 4-5 gas pumps starts. Let it warm up a bit. Drove, all is good. Came back to the house idled in the driveway. Unplugged the ICS plug and it died. Plugged it back in, started the cruiser just fine. Drove again a couple laps around the neighborhood did fine drove as expected. Came back to the house. Idled in the driveway pulled choke all the way out. Then disconnected the ICS plug and it died again. Same way with no choke applied. Pretty instant. Plugged it back in and it started right up. Drove a couple mor laps no issue.

Should I have that cut white wire covered? Could it be touching the body of the carb and confusing something? Does the white wire mod look right?

 

[Gretsch]

Could it be touching the body of the carb and confusing something?

I don't see how. Its just a ground. I personally wouldn't have cut the wire but I think what you have done works. If it clicks still with key on, then you likely have not broken anything. Easy to put some E-tape on that end so its not exposed. But you have bypassed some of the emissions controls. I think the EC actually determines when to open and close the ICS based on several inputs it gets from other sensors. One is a vacuum switch which measures the vacuum change on decel to close the ICS, and I think another one is vehicle speed from coil. Lots of good information on here regarding how this all works so check those to make sure I am not talking out my backside. You have effectively bypassed all this stuff to keep the ICS open all the time. If that were to fix your issue, you could then put it back right go about seeing what else in that chain could be faulty. Your EC could just be bad. Solder re-flow fixed me but its not for everyone.

Since you are still smogged, I am not sure you want to run this way long term. Most people do this mod because of the desmog. I guess I would run this until you are confident in this being your issue. However, if I recall the timeline here, you did this and still had the problem. Still not convinced this is your issue.

Has the fuel level in the sight glass changed any since this started working?

 

[LandoNick]

I don't see how. Its just a ground. I personally wouldn't have cut the wire but I think what you have done works. If it clicks still with key on, then you likely have not broken anything. Easy to put some E-tape on that end so its not exposed. But you have bypassed some of the emissions controls. I think the EC actually determines when to open and close the ICS based on several inputs it gets from other sensors. One is a vacuum switch which measures the vacuum change on decel to close the ICS, and I think another one is vehicle speed from coil. Lots of good information on here regarding how this all works so check those to make sure I am not talking out my backside. You have effectively bypassed all this stuff to keep the ICS open all the time. If that were to fix your issue, you could then put it back right go about seeing what else in that chain could be faulty. Your EC could just be bad. Solder re-flow fixed me but its not for everyone.

Since you are still smogged, I am not sure you want to run this way long term. Most people do this mod because of the desmog. I guess I would run this until you are confident in this being your issue. However, if I recall the timeline here, you did this and still had the problem. Still not convinced this is your issue.

Has the fuel level in the sight glass changed any since this started working?

No, no fuel change in window. Drove it a couple miles today and no issue. Stumped. Let it go until it happens again

 

[LandoNick]

Could a clogged or restricted cat have these effects? How can I test the cat? Temp range? On the exhaust? The reason I ask is when the 60 was bucking and trying to die. There would be a backfire and it would start running ok.