97 K3500 7.4l spitting, sputtering, backfires, and stalls

[Agibson]

I'm new here so bear with me please. I have a 97 chevy k3500 pickup with 7.4l and automatic trans. It started spitting and sputtering backfires stalls out going down the the road it will shut off and start back on its own. I've replaced the distributor, plugs, wires, fuel pressure regulator, cps, fuel injectors, and ground straps that were missing. The crankshaft position sensor was the last thing I replaced it ran fine after I put in it in on the test drive. When I got in it the next morning same problems came back. I'm lost and need help please.

 

[Agibson]

And I check fuel pressure and it's at 58psi and about 48 to 50 running

 

[618 Syndicate]

Fighting the same intermittent issue with a 98 454
I've become convinced that there's a problem with the black box pcm itself in my case. Drove 200 miles yesterday running fine before it started missing and sputtering, eventually just died. I pulled over, it would crank but not start. (I have a separate hot-start issue that I will fix) Put a jump box on it, it fired right up and ran great the other 60 miles home.
Complete distributor, plugs, wires, tps, pcm, and crank sensor have all been changed in the last 1000 miles.
Gonna swap out the pcm and see if that solves it. It seems that there's an internal short in it.

 

[Agibson]

I was thinking that might be the problem or a bad wire somewhere around the icm.

 

[1998_K1500_Sub]

Have you checked for codes? Do so even if the SES light is off.

My first inclination would be to connect a laptop to it and monitor the sensor readings and fuel / spark commands while its running and when it's acting-up. I think this would tell you volumes, instead of throwing parts at it. Now, I understand that sometimes "throwing parts" is the easier route, but replacing parts comes with the risk of screwing something up and introducing another, new problem.

You mentioned "replaced ground straps that were missing". How do you know they were missing? How do you know you re-installed every one necessary?

Does the vehicle's electrical system show ANY evidence of prior tampering?...

- You mentioned "missing ground straps"
- Are there any loose or obviously new / replaced / disconnected wires elsewhere under the hood?
- (ditto) under the dash or at the base of the steering column?
- has the vehicle been operating in a salty environment that might have lead to connector corrosion? Oceanside? Northern states w/ winter salt?

You could try to swap out the PCM if you like (I've see your other post here about the PCM https://www.gmt400.com/threads/flagship-one-pcm.58826/). I would be inclined to try one from a junk yard, provided they can assure you it's for the same engine / trans combo.

 

[Agibson]

The one ground from the engine to frame was broken. The ground on the passenger side from cab to chassis was completely missing.

I get a p1361 code low voltage ignition control module.

I live in Michigan so salt is normal.

Check under dash and under good for loose or broken wires couldn't find any.

I wasn't just throwing parts at.
Started with tune up and broke the cap
mounting screws so had to replace distributor. So I figured while I had the upper intake off I might as well do the pressure regulator, and injectors.

The only tampering of the wiring is a strobe light, fog lights, and trailer brake controller

 

[Agibson]

The truck didn't have the drivers inner fender well in it for a little while this winter. So I was think maybe the pcm got water in it a damaged it.

 

[618 Syndicate]

For clarity's sake, I'm not saying our issues are the same, or suggesting that you should buy a new PCM without further investigation. I'm just saying I'm reasonably sure that's what my issue is, and we have some similar symptoms.
I've had my codes pulled, addressed the issues they reflect, and basically the only thing left is the PCM.

 

[Agibson]

I understand that I'm just trying to get help for the issues I'm having. This is the fifth one of these trucks and have never ran into an issue like this.

 

[618 Syndicate]

If you have access to a scanner live data would be helpful.