Engine Stalling (1 Viewer)

[Atexsouth]

I passed emissions here in Denver once I discovered and removed a BB in the EGR hose. The truck would sputter while driving, so I put a BB back in the hose when I returned home, and the truck ran fine.

However a month or so after that the truck began stalling off and on, but it wasn’t very often, and would start right back up. Now it stalls more regularly so I have been trying to trouble shoot my issue.

Back in August I was in Ouray at the Solid Axel Summit, and @abtx4x4 showed me what hoses to switch on my charcoal canister thinking that check valve was causing fuel starvation, which I did and it ran great for two weeks.
Then @2mointainfish reached out and helped walk me through removing the ICS or FCS solenoid from the carb, inspect the o-ring, spray carb cleaner into the port, and reinstall, which I also did. The problem however is still there.

Here is an outline of what I am experiencing:

• Truck starts fine, and idles with no problems at around 500 to 600 rpm
• Drives great in downtown like conditions for 20 to 30 mins
• As I am coming to a stop in neutral it stalls
• In order to restart I must pull the choke out all the way and press on the gas pedal
• It drives with a slight sputter in 2nd gear, and will stall again when I go to stop in neutral
• In order to prevent stalling I must keep the choke out so the engine does not drop below 1000 rpm
• Drives with no problems with choke out for another 20 to 30 mins
• I then push the choke back in all the way, and I drives fine with no stalling issue

Any thoughts or ideas you have would be very much appreciated.

 

[Atexsouth]

I passed emissions here in Denver once I discovered and removed a BB in the EGR hose. The truck would sputter while driving, so I put a BB back in the hose when I returned home, and the truck ran fine.

However a month or so after that the truck began stalling off and on, but it wasn’t very often, and would start right back up. Now it stalls more regularly so I have been trying to trouble shoot my issue.

Back in August I was in Ouray at the Solid Axel Summit, and @abtx4x4 showed me what hoses to switch on my charcoal canister thinking that check valve was causing fuel starvation, which I did and it ran great for two weeks.
Then @2mointainfish reached out and helped walk me through removing the ICS or FCS solenoid from the carb, inspect the o-ring, spray carb cleaner into the port, and reinstall, which I also did. The problem however is still there.

Here is an outline of what I am experiencing:

• Truck starts fine, and idles with no problems at around 500 to 600 rpm
• Drives great in downtown like conditions for 20 to 30 mins
• As I am coming to a stop in neutral it stalls
• In order to restart I must pull the choke out all the way and press on the gas pedal
• It drives with a slight sputter in 2nd gear, and will stall again when I go to stop in neutral
• In order to prevent stalling I must keep the choke out so the engine does not drop below 1000 rpm
• Drives with no problems with choke out for another 20 to 30 mins
• I then push the choke back in all the way, and I drives fine with no stalling issue

Any thoughts or ideas you have would be very much appreciated.

@2mountainfish

 

[OSS]

It could be a couple things, but if the EGR valve actually is actuating (though you said you plugged it) it can easily stick open while driving on the freeway and stall the engine from the big vacuum leak it creates. To rule that out, drive with a vacuum gauge attached to the intake manifold and watch it the next time the engine conks out. If the vacuum is low at the time of death- examine what's going on with the EGR system. Specifically the valve.

One way or another, the engine is getting starved of fuel when it conks out. If you have an all stock Aisin carburetor, the choke knob is only a throttle positioner when the engine is warm, exactly the same as pushing down slightly on the gas pedal. Doesn't act as a choke (when warm).

Try setting the engine idle speed to 750 rpm instead of 650 when warm. The 2F likes a slightly faster idle than 650 rpm. That won't fix the problem, but it's helpful anyway.

 

[Gretsch]

I had symptoms similar to yours when my ICS was not actuating properly. My issues seem to have been fixed by fixing the poor grounds at the emissions computer for the ICS. The issue was so intermittent that it was really hard to diagnose. I actually pinpointed it being the ICS by starting the truck. getting it warm and idling, and unplugging the ICS from its electrical plug thus closing it and starving the engine for fuel. The engine sounded exactly the same as when it would die at stop lights. So was able to force the truck into that condition. Plugging the ICS back in would bring the truck back to normal idle. But the same thing as you describe. Pulling choke out or giving the truck some gas kept it running without dying. Running the A/C allowed the A/C idle up to keep the engine running as well. Basically anything giving it gas would keep it going. Without choke/throttle of any sort, the engine would die. I upped my idle as @OSS suggests and it runs much happier there. You can try the unplug ICS test I described above when you can get it to idle. Lots of folks say to turn on key (without engine running)and unplug and plug the power cable for the ICS to hear for a click. Mine always clicked doing that so I never found that useful. I did the ICS ground bypass mod on mine for a bit to see if the issue went away. It did so I knew bad grounds must be the problem. I re-flowed the solder on the emissions computer and the problem is now gone for over a year. I am not saying this is the same issue you are seeing, but it sounds similar. Do you get any bucking of the engine at highway speeds? Like hitting a wall repeatedly at 60Mph?

 

[Atexsouth]

No bucking on the highway. Actually drives really well at higher speeds. I also plugged and unplugged my ICS with the key on and hear clicks.
@OSS I also on advice replaced the EGR modulator while trying to pass emissions. It was obviously pulled from another truck, and I’m not entirely sure it is even good. Could that cause the EGR vacuum leak?

 

[OSS]

The EGR leak I'm referring to is the EGR valve getting stuck open after driving a while on the highway. Mine used to do it all the time. Power is fine when driving when valve is stuck open, but once gas is let off & transmission put in neutral (so the engine drops to idle speed) the engine will conk out because the valve didn't close. It's easy to see if that's the problem by driving with a vacuum gauge and noting what it does when the engine starts to conk out . If the EGR valve is stuck open, you'll see very low vacuum before it stalls

 

[Gretsch]

I also plugged and unplugged my ICS with the key on and hear clicks.

Again, I always heard clicks with mine as well. Could never get it to not click with engine off. I could even come in off the road after just having it stall, shut it down, jump right out and test the ICS. It always clicked, making me think it was something else for a time. Tried the ICS ground mod and never had an issue after that. It was taunting me. Thus the name for my truck in my signature. HTH.

 

[Atexsouth]

It could be a couple things, but if the EGR valve actually is actuating (though you said you plugged it) it can easily stick open while driving on the freeway and stall the engine from the big vacuum leak it creates. To rule that out, drive with a vacuum gauge attached to the intake manifold and watch it the next time the engine conks out. If the vacuum is low at the time of death- examine what's going on with the EGR system. Specifically the valve.

One way or another, the engine is getting starved of fuel when it conks out. If you have an all stock Aisin carburetor, the choke knob is only a throttle positioner when the engine is warm, exactly the same as pushing down slightly on the gas pedal. Doesn't act as a choke (when warm).

Try setting the engine idle speed to 750 rpm instead of 650 when warm. The 2F likes a slightly faster idle than 650 rpm. That won't fix the problem, but it's helpful anyway.

Pardon my ignorance, but where on the intake manifold do I attach a vacuum gauge? Currently searching for the answer.

 

[OSS]

where

Attach it where the AC idle up vacuum hose normally goes. Remove that small vacuum hose & connect the gauge's hose to the pipe. Very back of cylinder head. See pic

 

[Gretsch]

Attach it where the AC idle up vacuum hose normally goes. Remove that small vacuum hose & connect the gauge's hose to the pipe. Very back of cylinder head. See pic
View attachment 2079063

Man is that your Engine bay @OSS? So clean!!!

 

[Atexsouth]

Man is that your Engine bay @OSS? So clean!!!

That was my first thought!

 

[OSS]

was

 

[Atexsouth]

Attach it where the AC idle up vacuum hose normally goes. Remove that small vacuum hose & connect the gauge's hose to the pipe. Very back of cylinder head. See pic
View attachment 2079063

So, I don’t appear to have a small AC idle up port, but a larger diameter hose attaching straight to that accordion piece. It’s much larger than my vacuum gauge hose.

 

[Atexsouth]

I should mention this is a California truck (84) that did not come with factory AC.
I did have factory AC installed by Proffitt’s last year.

 

[2mountainfish]

I should mention this is a California truck (84) that did not come with factory AC.
I did have factory AC installed by Proffitt’s last year.

Did you ever ground the ICS directly? @Robert Franzke eluded to the point I was trying to make about the emissions circuit board grounding intermittently. As far as the vacuum gauge, you can put a "T" in the hose that you do have and connect the gauge . When not testing, just cap it off.

 

[Atexsouth]

Did you ever ground the ICS directly? @Robert Franzke eluded to the point I was trying to make about the emissions circuit board grounding intermittently. As far as the vacuum gauge, you can put a "T" in the hose that you do have and connect the gauge . When not testing, just cap it off.

Plan on doing that today.
This morning I hooked up the vac gauge to where the brake booster hose is (picture I attached above) got a late timing reading. Can timing alone cause my engine stall? Sorry for dumb questions, but I’m no mechanic. Trying to learn though!

 

[OSS]

The point of connecting a vacuum gauge to the engine is to see what the vacuum is doing when driving & it conks out (if EGR valve is sticking open). You'll need to connect the gauge with a Tee fitting with a longer vacuum hose to get the vacuum gauge into the cab to see it while you're driving. You need the big brake booster hose connected too (thus a tee fitting) otherwise it will be very difficult to stop.

What altitude are you at?

 

[Atexsouth]

The point of connecting a vacuum gauge to the engine is to see what the vacuum is doing when driving & it conks out (if EGR valve is sticking open). You'll need to connect the gauge with a Tee fitting with a longer vacuum hose to get the vacuum gauge into the cab to see it while you're driving. You need the big brake booster hose connected too (thus a tee fitting) otherwise it will be very difficult to stop.

What altitude are you at?

Denver - 5280

 

[OSS]

Also check the function of the High Altitude Compensation system (HAC). The emissions manual has a step by step procedure. Easy to check.