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1995 GMC Sierra K1500 5.7 | Problems when it’s warm

Kameron

By Kameron
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Kameron Enthusiast

Kameron

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Hello, I have a 1995 GMC Sierra K1500 5.7 liter.

 

The problem I am having with my truck is only observed when it is warm, when the temp reaches ~170F, it will start cutting out when it reaches 1800 rpm, then as it gets warmer it’ll start doing the same thing at 1500 rpm, and the cycle keeps going until the truck eventually chokes itself out and completely shuts off. When cold it will idle and run COMPLETELY fine, it will not cut out at all and will run like an absolute champ. When warm and idling it’ll also do the same thing as mentioned above, it’ll choke itself out. I have had the truck at 75 mph when cold and there’s not a single problem, though I can’t say the same when it eventually warms up. I did the paper clip method, as I could not find anybody who had an OBD-1 code scanner, and it showed a code 32. I cleaned the EGR valve because it was stuck, and made sure the plunger worked. I also put a lower degree thermostat. Also I should mention, I have cleaned the idle air control valve and have tested the TPS, which when testing, checked out good. I rechecked the fuel pressure and it’s within tolerance. Prior to this work I’ve done to the truck, I purchased it non-running with a bad transmission pump, replaced the pump, transmission works perfect. 

This is what I’ve done so far:

-New 195 degree thermostat

-New fuel pump

-New fuel filter

-New Distributer Cap 

-New Rotor Button

-New Spark plugs and wires

-New ignition control module (Noted: When I replaced the ignition control module, it ran flawlessly at any temperature for about 100 miles, then the truck sat for about 4 days, when crunk up and drove again, as it got warmer it started cutting out again as it did before)

- Replaced both temperature ascending units

 

Any help would be GREATLY appreciated!!

Kameron Enthusiast

Kameron

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1 hour ago, riverbanks said:

I would swap that module again,or change the coil

I had forgot to include that I’ve changed the coil. You’re not the first person to tell me to swap the module, yesterday my father was saying the same thing. I haven’t ever been sold a defective part before, but it is all a possibility, I will keep the forum updated. Thank you!

riverbanks Senior Enthusiast

riverbanks

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Only cause you mentioned,100 miles, just fine,but,if the symptoms were the same with the first one,it's good, you could try unplugging the map sensor electric connection and test drive,just to see if it was going flaky and leaning it out

Kameron Enthusiast

Kameron

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On 10/25/2020 at 9:56 AM, diyer2 said:

Swap the ignition module. 

Just swapped the ignition module and it’s doing the same thing. Never encountered a problem like this... I officially have no clue what it could be. Replaced the coil on it again as well. No help there. 

riverbanks Senior Enthusiast

riverbanks

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Hmm, sounded like heat/electric breakdown,so,same with egr, is that not able to close with underhood heat, binding?

Kameron Enthusiast

Kameron

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On 10/28/2020 at 9:23 PM, riverbanks said:

Hmm, sounded like heat/electric breakdown,so,same with egr, is that not able to close with underhood heat, binding?

Well. I’ve been doing research for the past couple of days and I just cannot find another individual who’s encountered the exact same problem as I am. Ever since I cleaned the EGR, the service engine light hasn’t came on. Tried reading any codes, all it’s showing is, 12, and that’s code for normal. My neighbor said it could be something to do with the computer itself, though he didn’t go into much detail, so I don’t know about the credibility of that. If I am able to, I will post videos soon of what the truck is exactly doing. It boggles me.

riverbanks Senior Enthusiast

riverbanks

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That's why your on a forum,stuff doesn't break the same way Everytime,so,I mentioned earlier, unplug the map,try it, make it go into open loop, better? look for cracked vacuum line to it,other is,if you are lean, unplug cts,rich is default in pcm,it helps to narrow it down

Kameron Enthusiast

Kameron

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I took a video of what my truck is doing, the video, though, is too large to post on the forum. The link is below, the video can gives better detail and explanation than I ever could.

 

riverbanks Senior Enthusiast

riverbanks

Posted
Posted

That truck has the oil pressure sensor right behind distributor, correct?that's the only item I can think of,that you touched the connection during distributor work,it is tied to fuel pump operation,they do fail,short to ground internally,or partial in your situation

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Kameron Enthusiast

Kameron

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18 hours ago, riverbanks said:

That truck has the oil pressure sensor right behind distributor, correct?that's the only item I can think of,that you touched the connection during distributor work,it is tied to fuel pump operation,they do fail,short to ground internally,or partial in your situation

Dude you are an absolute lifesaver!!!! Something so so so so so so so simple, but I would have NEVER thought to check it. If you would’ve never brought it to my attention, I would’ve never thought of it for the months to come. Thank you man, you’ve earned my respect and the best answer!!

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