1988 chevy k2500 idles perfect in park and Neutral but dies in gear.

[scornedlotus]

Hi all I'm having issues with my 1988 k2500 stalling in reverse or drive, but idles perfect in park or neutral . "Edit for info" it's a 5.7 350 small block ac delete.

For reference on what's going on when I got the truck it ran and drove okay, wasn't perfect but never stalled on me. Since I got the truck I've slowly worked on it step by step to insure nothing I did was a issue.

First step oil change first thing any new to you car should be done, spark plugs, muffler, gas cap that seals again and locks now... no issues through these steps. Truck never stalled on me either after completing said steps.

However a big problem I didn't know about till two months after owning the truck, the previous owner cored out the old thermostat because it froze shut. When I bought the truck I thought he said he replaced it. However talking to him a couple months later he said no he cored it, so I put two and two together and realized he didn't put a cheap thermostat in which is why the temp always read low... it couldn't read the right temp

So I replaced the thermostat and well I was at it the pcv valve because I realized when I did the oil change I didn't replace it... now all of a sudden the truck will idle in park zero issue. Neutral zero issue, I put the truck in reverse and instantly sluggish wanting to die without any help with help idles and won't die but not happy about it.
Drive is a little different sometimes it will play nice on its own others the moment you have zero moment the truck dies but driving isn't a issue she drives amazing...
THE ONLY BIG THING OF NOTE I CAN ADD:
When it does idle in drive or reverse for a moment before stalling out with out straight shutting off. She fights to stay alive then just cuts out straight out of nowhere and the volts are anywhere from 1/4 the tack gauge to half where it normally is bouncing back and forth back and forth, battery is brand new and test great same for the alternator, and voltage regulater.

Thank you so so so much ahead of time for anyone and everyone who can help.

Edit, sorry I'm thinking of things as I'm working on the truck, when the truck dies it refuces to restart again right of the bat if I'm patient and wait about 15-30s it will start with little fight but no where near as being pissed and trying to start it right away it acts basically dead. But battery is perfectly fine again same as the alt and voltage regulater

 

[Sean Buick 76]

Fuel pressure would be my first check. Second would be the fuel pressure regulator at the TBI, I had one fail that caused similar issues.

 

[WICruiser-97]

When you say won't start do you mean won't fire and run or will not crank? Your comment regarding the battery leads me to suspect that it doesn't crank but that's a whole different diagnosis pathway than the idle/stall problem typically associated with not starting after a stall.

 

[scornedlotus]

When you say won't start do you mean won't fire and run or will not crank? Your comment regarding the battery leads me to suspect that it doesn't crank but that's a whole different diagnosis pathway than the idle/stall problem typically associated with not starting after a stall.

It cranks, but it's a weak crank like the battery isn't charged, however if I hook a voltage reader and other things everything is fine tested at autozone, oreillyauto, napa, all them say battery is good same as the alt and voltage regulater. But thats if I try to crank right away... like I said if I let it sit about 15-30s it will crank a lot better but not the same as resetting everything and it running like a new truck for about 5 miles then goes back to being weak again

Fuel pressure would be my first check. Second would be the fuel pressure regulator at the TBI, I had one fail that caused similar issues.

Thank you I appreciate the suggestion I will look into this, I haven't check over that yet. The fuel pump works I can hear it turn on and prime the lines so I would assume it's the regulater at the tbi if it is anything

 

[scornedlotus]

Fuel pressure would be my first check. Second would be the fuel pressure regulator at the TBI, I had one fail that caused similar issues.

When you say won't start do you mean won't fire and run or will not crank? Your comment regarding the battery leads me to suspect that it doesn't crank but that's a whole different diagnosis pathway than the idle/stall problem typically associated with not starting after a stall.

So I was just doing a little digging into the way the previous owner by passed the wiper because he said the wiper controls died but blinkers still worked
Would this by chance be a cause for the truck to keep randomly stalling out all of a sudden?? Referring to the photo posted with the response.

I haven't had much time to doing any looking into the truck till lately I was just using it till now. When the stalling started to happen then it sat for a little bit and I switched to my s10 since I didn't need the big truck till now I have to move my trailer thats to big for my s10 and need to figure this problem out.

Edit just talk to my brother he said as much as the issue in the photo should be addressed he said short term 99% of the time thats fine. Won't hurt anything but should be fix soon. He thinks it's the icm over anything. Since fleshing the brain works for about 5 mins.

 

[WICruiser-97]

If it cranks slow after it stalls but okay after a little while there may be something increasing the resistance to rotation. Things that change over time would include pressure bleeding off somewhere in the engine or transmission. Is it possible that the stall is due to flooding and some of the cylinders are getting enough fuel to fill the combustion chamber? Seems like a stretch but easy enough to check by checking the condition of the plugs after it has stalled before you try to start it again.

 

[scornedlotus]

If it cranks slow after it stalls but okay after a little while there may be something increasing the resistance to rotation. Things that change over time would include pressure bleeding off somewhere in the engine or transmission. Is it possible that the stall is due to flooding and some of the cylinders are getting enough fuel to fill the combustion chamber? Seems like a stretch but easy enough to check by checking the condition of the plugs after it has stalled before you try to start it again.

The icm was tested and pass 5 out of 20 sequential test and is part of the problem right now before I take anymore steps to solve the issue I will waiting for my pay check to replace that part first