advice needed, unknown stalling issue

Andrew Wheeler · September 13, 2020

Having some issues with my '93 C1500 stalling and dying. It started last month when I was replacing parts to get my truck back on the road after sitting for a long time without much use. After I had managed to get the A/C blowing cold air again (freon, compressor pigtail and tensioner pulley) I noticed that the idle would slow and get choppy, even stalled and died once. I went back to work on it and ended up putting in a brand new Delco egr valve, IAC, fuel pressure regulator assembly, emissions tubing, intake adaptor, intake and egr solenoid. Even with all the parts the truck will still stall with or without the ac engaged and gets significantly worse with the egr solenoid plugged in. As in it stalls terribly at very light throttle since it looks like the valve completely closes when you hit the throttle just right. The engine is a jasper 350 crate with around 80k miles and Ive replaced every single sensor on it at some point or another. I should also mention that before this work was done I'd had the egr blocked off completely with a plate and an adjustable fuel pressure regulator in. I just wanted to get it back to stock once the stalling started so I could have a reliable truck again. At this point i'm worried the problem may be in the pcm or prom since it was running great most of the day with the solenoid unplugged then started stalling again after sitting for an hour turned off. I'm stumped

Andrew Wheeler · September 17, 2020

Update: I've installed a rebuilt ECM using the original PROM and issue still seems to exist albeit it's a little better and transmission shifts much smoother. Think I'll try to take that $90 delco egr back off and block it off again smh. Love wasting money

Andrew Wheeler · September 22, 2020

Chased the issue to the ignition system. I'm pretty sure this is an indicator of what the problem is. I know nobody is going to post a response on here, but I'll go ahead and try anyway. Doesn't seem to be any good ck forums out there anymore

KINGENGINEMAINTENANCE · September 27, 2020

Agree, hard to find good help anywhere these days. Definitely replace that distributor cap. Consider putting a new fuel pump AND STRAINER. Strainer filter doesn't usually come with a new fuel pump you would have to order it as well. I have seen some nasty strainer filters on these trucks which can certainly cause a stall issue, seen it first hand. Good luck dude Cheers

txab · September 27, 2020

I'd check fuel pressure and flow rate

Tom_1991 · October 2, 2020

Did you checked ignition control module (ICM)?

My mechanic told me it may fail after very long time sitting.

My 94 Suburban with 454 TBI used to have a failure ICM, but symptom is not same with you.

It sometime suddenly make the engine wrong timing, or simply stall when vehicle was moving on highway.

Just a reminder.

Andrew Wheeler · October 2, 2020

Icm, distributor cap, rotor, plug wires, magnetic pickup coil were replaced a week ago. I put in an airtex fuel pump and strainer in, but that was around 10 years ago.

Andrew Wheeler · October 17, 2020

Many new parts later and I'm still having the stalling problem. Seemed to get much better and hasn't died any with a new ignition coil. Also replaced distributor, iat sensor, fuel injectors and map sensor. I'm starting to think it may be a worn timing chain since it's probably at least 15 years old with 80-90k miles on it. The reason I think this is that when I was setting the timing I noticed the timing notch jumping around quite a bit. My question is, how do I find out which size of timing chain to buy? Or do I just need to go ahead and start pulling parts and find out the hard way

Andrew Wheeler · October 25, 2020

Another update in case anybody is listening. Decided against the timing chain after checking again and not noticing any jumping whatsoever from the timing mark. Also I don't think it's a burnt valve. I haven't done a compression test, but I tried the paper test on the oil filler hole and both exhaust pipes. Have ordered a new intake manifold gasket and plan to clean it up and replace the tb gaskets as well. Tried to use maf cleaner to detect vacuum leaks, but there's so much grime around the manifold it's hard to tell any difference.