Stalling when placed under a light load and/stopping

I am having issues with my 1993 c2500 (Light Duty) TBI 350.
This started about a month ago like this -
Quick startup, no issues, pull out of driveway and accelerate to first stop.
Enine stalls dead. Put in neutral, turn key to crank, starts up and drives.
Hesitation/bogging feeling at around 1500 to 2000 rpm, no stalling.
Bogging goes away after a few times, does not return with subsequent driving through the day.

About 2 weeks ago -
Early stalling issue is not occurring anymore, bogging is a bit more consistent however, still goes away after a few times and still not an issue with subsequent starts and stops.

2 days agon - no stalling issues, some now "reliable" bogging on the startup and then disappears. Took a 20 minute freeway drive with no issues until I made a stop at a drive thru. In drive and stopped with foot on the break, vehicle dies instantly as if all power/spark was cut out.

I put into drive and crank car, starts and stumbles dead, try again and the same.
Now the strange part to me is that if I turn the ignition off as if i am going to pull the key out - and then start the car, it will start up and run.

At this point the car will start and run, it now will lose power (cut out dead) on deceleration like coasting or a slow down to a red light, and will start up by going to the ignition off position and then cranking.

I was lucky to make it home the other day, and it started right up yesterday morning with no issues, idles just fine and i let it run for a while in the driveway looking for knocks or pings.

CEL is not on, but I do have a occasional flash from it once in a while for a code 43 that from what i read could be a knock sensor or anywhere in between.... this has come and gone on occasion while driving in the last 2 years, but I have never felt a knock or any issue before.

I am ready now ready to throw parts st this....lol


Thanks for reading this through and any help in advance.

Check your fuel pressure. Replace your fuel filter if you haven't recently.

RQ Jay said:

I am ready now ready to throw parts st this....lol

Click to expand...

Mistake in philosophy. TEST before replacing. This almost always saves money, saves frustration, and saves disappointment.

It's the rare (or lucky) situation where replacing parts without testing them works out well.

RQ Jay said:

I am having issues with my 1993 c2500 (Light Duty) TBI 350.
This started about a month ago like this -
Quick startup, no issues, pull out of driveway and accelerate to first stop.
Enine stalls dead. Put in neutral, turn key to crank, starts up and drives.
Hesitation/bogging feeling at around 1500 to 2000 rpm, no stalling.
Bogging goes away after a few times, does not return with subsequent driving through the day.

About 2 weeks ago -
Early stalling issue is not occurring anymore, bogging is a bit more consistent however, still goes away after a few times and still not an issue with subsequent starts and stops.

2 days agon - no stalling issues, some now "reliable" bogging on the startup and then disappears. Took a 20 minute freeway drive with no issues until I made a stop at a drive thru. In drive and stopped with foot on the break, vehicle dies instantly as if all power/spark was cut out.

I put into drive and crank car, starts and stumbles dead, try again and the same.

Click to expand...

So far, this is sounding like a fuel pressure issue, or an IAC issue. The previous suggestion to verify fuel pressure and replace fuel filter is a good one.

Also, connect a scan tool, look for codes, but especially look at the data stream. Find out what the computer is trying to tell you.

RQ Jay said:

Now the strange part to me is that if I turn the ignition off as if i am going to pull the key out - and then start the car, it will start up and run.

Click to expand...

You may need to dig out the voltmeter and assure that the ignition switch (and security system, if the vehicle has one) is working properly--no intermittent contact.

RQ Jay said:

At this point the car will start and run, it now will lose power (cut out dead) on deceleration like coasting or a slow down to a red light, and will start up by going to the ignition off position and then cranking.

Click to expand...

Any chance the Torque Converter Clutch is sticking "on", so it forces the engine to stall as vehicle speed comes down?

Maybe it's stuck "on" until you turn off the ignition. Worth checking.

RQ Jay said:

CEL is not on, but I do have a occasional flash from it once in a while for a code 43 that from what i read could be a knock sensor or anywhere in between.... this has come and gone on occasion while driving in the last 2 years, but I have never felt a knock or any issue before.

Click to expand...

The service manual will have a procedure for that Code 43.

Schurkey said:

Mistake in philosophy. TEST before replacing. This almost always saves money, saves frustration, and saves disappointment.

It's the rare (or lucky) situation where replacing parts without testing them works out well.



So far, this is sounding like a fuel pressure issue, or an IAC issue. The previous suggestion to verify fuel pressure and replace fuel filter is a good one.

Also, connect a scan tool, look for codes, but especially look at the data stream. Find out what the computer is trying to tell you.


You may need to dig out the voltmeter and assure that the ignition switch (and security system, if the vehicle has one) is working properly--no intermittent contact.


Any chance the Torque Converter Clutch is sticking "on", so it forces the engine to stall as vehicle speed comes down?

Maybe it's stuck "on" until you turn off the ignition. Worth checking.


The service manual will have a procedure for that Code 43.

Click to expand...

Thank you, I plan to approach this with a bit of discretion and diagnose...
I am joking about throwing parts because its typical that people do that readily.
All valid points I had thought about to start checking, however your mention of possible torque convertor clutch sticking is not something i have heard of before, and unsure how to exactly check for that?
Also, do you have a recommended scan tool that has a reasonable cost?
Thanks!

Erik the Awful said:

Check your fuel pressure. Replace your fuel filter if you haven't recently.

Click to expand...

I was anticipating a trip to Oreillys to rent a fuel pressure tester first, I am hoping that the problem rears its head in the standard operations and not intermittently... The stall out nly happens at cruise speed and never when at idle or park.
I really dont intend to throw parts, but a fuel filter is pretty cheap to get done, worth the time.

Just a note, I did notice the thermatic vent in the air filter housing no longer opens when hot, looks to only stay closed. I dont think what i have experienced is the engine "choking"... is that possible,?

I can see that being a higher-speed issue. No problem at idle or low speed, aside from the throttle body getting overly-warm from the hot incoming air.

Yeah, you need to attend to that. Ideally, it'd be fixed and functional, but if Glendale is as dry as I suspect...maybe you'd just disable the thing. The main purpose is to prevent carb icing when it's ~40 degrees F. and raining. Secondary purpose is to promote fuel vaporization when weather is cool/cold.

RQ Jay said:

do you have a recommended scan tool that has a reasonable cost?

Click to expand...

Do you have a laptop? You can get a functional means of data logging, troubleshooting, and programming (should you choose) for minimum investments. For data logging, all you need is an ALDL to USB cable, TunerPro RT v.5x and the corresponding definition file for your PCM. For ~$60 you can hook up and go

Schurkey said:

but if Glendale is as dry as I suspect...maybe you'd just disable the thing

Click to expand...

Except for Monsoon season it's dry - during Monsoon, it's above 54* dew point but 90*+ ambient. RIght now I have 97* and 12% humidity.

Hey @RQ Jay where in Glendale are you?

PlayingWithTBI said:

Do you have a laptop? You can get a functional means of data logging, troubleshooting, and programming (should you choose) for minimum investments. For data logging, all you need is an ALDL to USB cable, TunerPro RT v.5x and the corresponding definition file for your PCM. For ~$60 you can hook up and go


Except for Monsoon season it's dry - during Monsoon, it's above 54* dew point but 90*+ ambient. RIght now I have 97* and 12% humidity.

Hey @RQ Jay where in Glendale are you?

Click to expand...

Thank you. I have not updated my profile but I have left Glendale in March.
I used to live across the street from Cardinal Stadium and am now living in the suburbs of St. Louis MO.
Big changes...nice ones though.

RQ Jay said:

Thank you. I have not updated my profile but I have left Glendale in March.
I used to live across the street from Cardinal Stadium and am now living in the suburbs of St. Louis MO.
Big changes...nice ones though.

Click to expand...

I've been to Glendale, and I live not far from St Louis, you're wrong.....lolol just kidding. Welcome to the Midwest.